Plurality of autonomous mobile robots and controlling method for the same

ABSTRACT

The present disclosure relates to a plurality of autonomous mobile robots. A plurality of autonomous mobile robots comprise a first mobile robot including an antenna configured to transmit and receive signals, and a second mobile robot including a first antenna and a second antenna disposed on a front area of a main body thereof to transmit and receive signals to and from the antenna of the first mobile robot. The second mobile robot comprises a control unit configured to determine a relative position of the first mobile robot using the signal received by the first antenna and the second antenna.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean PatentApplication No. 10-2019-0020080, filed on Feb. 20, 2019, the disclosureof which is herein incorporated by reference in its entirety.

BACKGROUND OF THE DISCLOSURE 1. Technical Field

The present disclosure relates to a plurality of autonomous mobilerobots.

2. Description of the Related Art

Generally, a mobile robot is a device that automatically performs apredetermined operation while traveling by itself in a predeterminedarea without a user's operation. The mobile robot senses obstacleslocated in the area and performs its operations by moving close to oraway from such obstacles.

Such mobile robot may include a robot cleaner that performs cleaningwhile traveling in an area.

The robot cleaner is a cleaner that performs cleaning while traveling byitself without a user's operation.

In this manner, with the development of such mobile robots capable ofperforming cleaning while traveling by themselves without users'operations, there is a need to make a plurality of mobile robots performcleaning in a collaborating manner without users' operations.

The prior art document WO2017-036532 discloses a method in which amaster robot cleaner (hereinafter, referred to as a master robot)controls at least one slave robot cleaner (hereinafter, referred to as aslave robot).

The prior art document discloses a configuration in which the masterrobot detects adjacent obstacles by using an obstacle detection deviceand determines its position relative to the slave robot using positiondata derived from the obstacle detection device.

In addition, the prior art discloses a configuration in which the masterrobot and the slave robot perform communication with each other via aserver using wireless local area network (WLAN) technology.

According to the prior art document, the master robot can determine theposition of the slave robot but the slave robot cannot determine theposition of the master robot.

Further, in order for the slave robot to determine (decide) the positionof the master robot using the configuration disclosed in the prior artdocument, the master robot must transmit relative position informationregarding the slave robot determined by the master robot to the slaverobot through the server.

However, the prior art fails to disclose such a configuration in whichthe master robot transmits relative position information to the slaverobot via the server.

In addition, even if it is assumed that the master robot transmitsrelative position information, the master robot and the slave robotcommunicate only through the server. Accordingly, such communicationwith the server may be disconnected when the master robot or the slaverobot is located at a place where it is difficult to communicate withthe server.

In this case, since the slave robot cannot receive the relative positioninformation from the server, it may be difficult for the slave robot todecide (determine) the relative position of the master robot, which mayprohibit smooth following control of the master robot and the slaverobot.

In order to perform smooth following control through communicationbetween a plurality of autonomous mobile robots, it is necessary todetermine whether the master robot is located at the front or at therear of the slave robot, or whether the slave robot is located at thefront or at the rear of the master robot.

However, since the prior art document merely discloses that the masterrobot transmits the relative position information to the slave robotthrough the server, it is impossible to determine whether the masterrobot is located at the front or at the rear of the slave robot, orwhether the slave robot is located at the front or at the rear of themaster robot.

SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is to provide mobile robots,capable of performing cleaning in an optimized manner without a user'sintervention, and a control method thereof.

Another aspect of the present disclosure is to provide mobile robots,wherein one of a plurality of mobile robots follows another robot of theplurality of mobile robots in an optimized manner, and a control methodthereof.

Still another aspect of the present disclosure is to provide mobilerobots capable of recognizing relative positions of a plurality ofmobile robots, irrespective of a communication state between theplurality of mobile robots and a server, and a control method thereof.

Still another aspect of the present disclosure is to provide mobilerobots capable of recognizing relative positions of a plurality ofmobile robots, by using only the least number of components and lowcosts, and a control method thereof.

Still another aspect of the present disclosure is to provide mobilerobots, each of which is configured to recognize a location of anotherrobot with respect to the front so as to perform smooth followingcontrol, and a control method thereof.

To achieve the aspects and other advantages of the present disclosure,there is provided a plurality of autonomous mobile robots, including afirst mobile robot having an antenna configured to transmit and receivea signal, and a second mobile robot having a first antenna and a secondantenna disposed on a front area of a main body thereof, the firstantenna and the second antenna being configured to transmit and receivesignals to and from the antenna of the first mobile robot. The secondmobile robot may comprise a control unit configured to determine arelative position of the first mobile robot using the signal received bythe first antenna and the second antenna.

In an embodiment disclosed herein, the first antenna and the secondantenna may be disposed to be symmetric to each other in right and leftdirections with respect to the front area of the main body.

In an embodiment disclosed herein, the first antenna and the secondantenna may be configured to receive signals transmitted in directionsexcept for a direction traveling from the front area of the main bodythrough the main body.

In an embodiment disclosed herein, an intensity of the signal receivedin the first antenna or the second antenna may be reduced when thesignal is received through the main body.

In an embodiment disclosed herein, an intensity of the signal receivedin the first antenna and the second antenna without passing through themain body after being output from the one antenna of the first mobilerobot may be stronger than an intensity of the signal received in thefirst antenna and the second antenna through the main body after beingoutput from one the antenna of the first mobile robot.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to output a first signal to the first mobilerobot through at least one of the first antenna or the second antenna,receive a second signal output from the one antenna of the first mobilerobot in each of the first antenna and the second antenna, and determinea first distance between the one antenna of the first mobile robot andthe first antenna and a second distance between the antenna of the firstmobile robot and the second antenna when the second signal is receivedin the first antenna and the second antenna.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine a first distance between the oneantenna of the first mobile robot and the first antenna and a seconddistance between the one antenna of the first mobile robot and thesecond antenna, based on the signals transmitted and received throughthe antenna of the first mobile robot and the first antenna and thesecond antenna of the second mobile robot, and determine twointersections between a first circle and a second circle. A radius ofthe first circle may correspond to the first distance and a center ofthe first circle may correspond to the first antenna. A radius of thesecond circle may correspond to the second distance and a center of thesecond circle may correspond to the second antenna.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine the relative position of the firstmobile robot based on an intensity of the signal received through thefirst antenna and the second antenna.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine two intersections between a firstcircle and a second circle. A radius of the first circle may correspondto a first distance between the antenna of the first mobile robot andthe first antenna and a center of the first circle may correspond to thefirst antenna. A radius of the second circle may correspond to a seconddistance between the antenna of the first mobile robot and the secondantenna and a center of the second circle may correspond to the secondantenna. The control unit may be configured to determine an intersectionlocated at a front of the second mobile robot of the two intersectionsas the relative position of the first mobile robot when the intensity ofthe signal received through the first antenna and the second antenna isequal to or greater than a reference value.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine an intersection located at a rearof the second mobile robot of the two intersections as the relativeposition of the first mobile robot when the intensity of the signalreceived through the first antenna and the second antenna is smallerthan the reference value.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine a position of the antenna of thefirst mobile robot as the relative position of the first mobile robot.

In an embodiment disclosed herein, the first mobile robot may comprisean Ultra-Wideband (UWB) tag to transmit and receive a UWB signal, andthe antenna of the first mobile robot may be electrically connected tothe UWB tag.

In an embodiment disclosed herein, the second mobile robot may comprisean Ultra-Wideband (UWB) anchor to transmit and receive a UWB signal, andthe first antenna and the second antenna of the second mobile robot maybe electrically connected to the UWB anchor.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine an arrangement state of the firstmobile robot and the second mobile robot based on an intensity of thesignal received through the first antenna and the second antenna.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to determine a direction in which the firstmobile robot is located with respect to a front of the second mobilerobot, based on a phase difference of the signal received through thefirst antenna and the second antenna.

In an embodiment disclosed herein, the second mobile robot may include afirst Ultra-Wideband (UWB) anchor connected to the first antenna, and asecond UWB anchor connected to the second antenna. The control unit ofthe second mobile robot may be configured to determine a directioninformation in which the first mobile robot is located with respect to afront of the second mobile robot, based on a phase difference between asignal received by the first UWB anchor through the first antenna and asignal received by the second UWB anchor through the second antenna.

In an embodiment disclosed herein, the control unit of the second mobilerobot may be configured to calculate a distance to the first mobilerobot, based on signals transmitted and received through at least one ofthe antenna of the first mobile robot, the first antenna of the secondmobile robot, or the second antenna of the second mobile robot, anddetermine the relative position of the first mobile robot based on thecalculated distance and the direction.

To achieve the aspects and other advantages of the present disclosure,there is provided a method for controlling a mobile robot, the methodcomprising determining a first distance between an antenna of the firstmobile robot and a first antenna of the second mobile robot and a seconddistance between the antenna of the first mobile robot and a secondantenna of the second mobile robot, respectively, when a signal isreceived through the first antenna and the second antenna of the secondmobile robot, determining, by the control unit, two intersectionsbetween a first circle and a second circle, the first circle having thefirst distance as a radius and the second circle having the seconddistance as a radius, and determining, by the control unit, one of thetwo intersections as the relative position of the first mobile robotbased on an intensity of the signal received in the first antenna andthe second antenna.

The present disclosure provides a plurality of autonomous mobile robotsthat a second mobile robot can accurately determine a relative positionof a first mobile robot.

The present disclosure provides a plurality of new autonomous mobilerobots, capable of reducing costs while improving accuracy in a mannerthat a second mobile robot determines a relative position of a firstmobile robot using one UWB tag, one UWB anchor and the least antennas.

The present disclosure provides a plurality of new autonomous mobilerobots, capable of accurately determining a relative position of a firstmobile robot using only two receiving antennas, by use of the fact thata signal can be received through a main body and intensity of the signalcan be attenuated.

The present disclosure calculates two intersections through a UWB moduleusing a UWB signal and the least antennas, so as to enable calculationof two accurate intersections and determination as to whether a firstmobile robot is located at the front or rear of the second mobile robotbased on intensity of a signal.

The present disclosure provides a plurality of autonomous mobile robots,capable of allowing smooth following travel by recognizing relativepositions thereof irrespective of a communication state with a serverbecause relative positions of a first mobile robot and a second mobilerobot can be determined by the first and second mobile robots.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating one embodiment of a robotcleaner according to an embodiment of the present disclosure.

FIG. 2 is a planar view of the autonomous mobile robot illustrated inFIG. 1 according to an embodiment of the present disclosure.

FIG. 3 is a lateral view of the autonomous mobile robot illustrated inFIG. 1 according to an embodiment of the present disclosure.

FIG. 4 is a block diagram illustrating exemplary components of anautonomous mobile robot according to an embodiment of the presentdisclosure.

FIG. 5A is a conceptual view illustrating a network communicationbetween a plurality of autonomous mobile robots according to anembodiment of the present disclosure.

FIG. 5B is a conceptual view illustrating an example of the networkcommunication of FIG. 5A according to an embodiment of the presentdisclosure.

FIG. 5C is a conceptual view illustrating a following travel of aplurality of autonomous mobile robots according to an embodiment of thepresent disclosure.

FIG. 6A is a conceptual view illustrating a follow-up registration and afollow-up control between a first mobile robot and a mobile device,according to an embodiment of the present disclosure.

FIG. 6B is another conceptual view illustrating the follow-upregistration and the follow-up control between the first mobile robotand the mobile device of FIG. 6A, according to an embodiment of thepresent disclosure.

FIG. 6C is another conceptual view illustrating the follow-upregistration and the follow-up control between the first mobile robotand the mobile device of FIG. 6A, according to an embodiment of thepresent disclosure.

FIG. 7A is a conceptual view illustrating a plurality of autonomousmobile robots in accordance with an embodiment of the presentdisclosure.

FIG. 7B is another conceptual view illustrating the plurality ofautonomous mobile robots of FIG. 7A in accordance with an embodiment ofthe present disclosure.

FIG. 8 is a conceptual view illustrating a method of determining adistance between a first mobile robot and a second mobile robot usingUWB modules in accordance with an embodiment of the present disclosure.

FIG. 9 is a flowchart illustrating a representative control methodaccording to an embodiment of the present disclosure.

FIG. 10 is a flowchart illustrating a part of the control method of FIG.9 according to an embodiment of the present disclosure.

FIG. 11A is a conceptual view illustrating the method of FIGS. 9 and 10,according to an embodiment of the present disclosure.

FIG. 11B is another conceptual view illustrating the method of FIGS. 9and 10, according to an embodiment of the present disclosure.

FIG. 12 is another conceptual view illustrating the method of FIGS. 9and 10, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Hereinafter, autonomous mobile robots according to the presentdisclosure will be described in detail with reference to theaccompanying drawings.

Hereinafter, description will be given in detail of embodimentsdisclosed herein. Technical terms used in this specification are merelyused for explaining specific embodiments, and should not be constructedto limit the scope of the technology disclosed herein.

First, the term “mobile robot” disclosed herein may be used as the samemeaning as ‘robot (for a specific function),’ ‘robot cleaner,’ ‘robotfor cleaning’ and ‘autonomous cleaner,’ and those terms will be usedequally.

A “plurality of mobile robots” disclosed in the present disclosure maybe used as a “plurality of robot cleaners” or “a plurality of cleaners”.Also, a “first mobile robot” may be named “first robot”, “first robotcleaner”, “first cleaner”, or “leading or master cleaner”. Further, a“second mobile robot” may be named as “second robot”, “second robotcleaner”, “second cleaner”, or “following or slave cleaner”.

FIGS. 1 to 3 illustrate a robot cleaner as an example of a mobile robotaccording to the present disclosure.

FIG. 1 is a perspective view illustrating one embodiment of anautonomous mobile robot 100 according to the present disclosure, FIG. 2is a planar view of the autonomous mobile robot 100 illustrated in FIG.1, and FIG. 3 is a lateral view of the autonomous mobile robot 100illustrated in FIG. 1.

In this specification, a mobile robot, an autonomous mobile robot, and acleaner that performs autonomous traveling may be used in the samesense. In this specification, a plurality of autonomous mobile robotsmay include at least part of configurations illustrated in FIGS. 1 to 3.

Referring to FIGS. 1 to 3, an autonomous mobile robot 100 performs afunction of cleaning a floor while traveling on a predetermined area byitself. Cleaning the floor disclosed herein includes sucking dust(including foreign materials) on the floor or mopping the floor.

The autonomous mobile robot 100 may include a cleaner main body 110, acleaning unit 120, a sensing unit 130, and a dust bin 140.

The cleaner main body 110 may include various components in addition toa control unit (not illustrated) for controlling the mobile robot 100.In addition, the cleaner main body 110 may include a wheel unit 111 fortraveling the autonomous mobile robot 100. The autonomous mobile robot100 may be moved or rotated forward, backward, left or right by thewheel unit 111.

Referring to FIG. 3, the wheel unit 111 may include main wheels 111 aand a sub wheel 111 b.

The main wheels 111 a may be provided on both sides of the cleaner mainbody 110 and may be configured to be rotatable in one direction oranother direction according to a control signal of the control unit.Each of the main wheels 111 a may be configured to be drivenindependently of each other. For example, each main wheel 111 a may bedriven by a different motor. Or, each main wheel 111 a may be driven bya plurality of different axes provided in one motor.

The sub wheel 111 b may support the cleaner main body 110 together withthe main wheels 111 a and may assist the traveling of the autonomousmobile robot 100 by the main wheels 111 a. The sub wheel 111 b may alsobe provided on a cleaning unit 120 to be described later.

The control unit may control the driving of the wheel unit 111, so thatthe autonomous mobile robot 100 is allowed to autonomously run thefloor.

Meanwhile, the cleaner main body 110 may include a battery (not shown)for supplying power to the autonomous mobile robot 100. The battery 190may be configured to be rechargeable, and may be detachably disposed ina bottom portion of the cleaner main body 110.

In FIG. 1, a cleaning unit 120 may be disposed in a protruding form fromone side of the cleaner main body 110, so as to suck air containing dustor mop an area. The one side may be a side where the cleaner main body110 travels in a forward direction F, that is, a front side of thecleaner main body 110.

In this drawing, the cleaning unit 120 has a shape protruding from oneside of the cleaner main body 110 to front and both left and rightsides. Specifically, a front end portion of the cleaning unit 120 may bedisposed at a position spaced forward apart from the one side of thecleaner main body 110, and left and right end portions of the cleaningunit 120 may be disposed at positions spaced apart from the one side ofthe cleaner main body 110 in the right and left directions.

As the cleaner main body 110 is formed in a circular shape and bothsides of a rear end portion of the cleaning unit 120 protrude from thecleaner main body 110 to both left and right sides, empty spaces,namely, gaps may be formed between the cleaner main body 110 and thecleaning unit 120. The empty spaces may include spaces between both leftand right end portions of the cleaner main body 110 and both left andright end portions of the cleaning unit 120 and each has a shaperecessed into the autonomous mobile robot 100.

If an obstacle is caught in the empty space, the autonomous mobile robot100 may be unmovable due to the obstacle. To prevent this, a covermember 129 may be disposed to cover at least part of the empty space.

The cover member 129 may be provided on the cleaner main body 110 or thecleaning unit 120. In an embodiment of the present disclosure, the covermember 129 may protrude from each of both sides of the rear end portionof the cleaning unit 120 and may cover an outer circumferential surfaceof the cleaner main body 110.

The cover member 129 may be disposed to fill at least part of the emptyspace between the cleaner main body 110 and the cleaning unit 120. Thecover member 129 may include a structure capable of preventing anobstacle from being caught in the empty space, or escaping an obstacleeven if the obstacle is caught in the empty space.

The cover member 129 protruding from the cleaning unit 120 may besupported on the outer circumferential surface of the cleaner main body110.

The cover member 129 may be supported on a rear portion of the cleaningunit 120 if the cover member 129 protrudes from the cleaner main body110. According to this structure, when the cleaning unit 120 is impacteddue to colliding with an obstacle, a part of the impact may betransferred to the cleaner main body 110 so as to be dispersed.

The cleaning unit 120 may be detachably coupled to the cleaner main body110. When the cleaning unit 120 is detached from the cleaner main body110, a mop module (not shown) may be detachably coupled to the cleanermain body 110 in place of the detached cleaning unit 120.

Accordingly, the user may mount the cleaning unit 120 on the cleanermain body 110 when the user wishes to remove dust on the floor, and maymount the mop module on the cleaner main body 110 when the user wants tomop the floor.

When the cleaning unit 120 is mounted on the cleaner main body 110, themounting may be guided by the cover member 129 described above. As thecover member 129 is disposed to cover the outer circumferential surfaceof the cleaner main body 110, a relative position of the cleaning unit120 with respect to the cleaner main body 110 may be determined.

The cleaning unit 120 may comprise a castor 123. The caster 123 mayassist the running of the autonomous mobile robot 100 and also supportthe autonomous mobile robot 100.

The cleaner main body 110 may include a sensing unit 130. Asillustrated, the sensing unit 130 may be disposed on one side of thecleaner main body 110 where the cleaning unit 120 is located, forexample, on a front side of the cleaner main body 110.

The sensing unit 130 may be disposed to overlap the cleaning unit 120 inan up and down direction of the cleaner main body 110. The sensing unit130 may be disposed at an upper portion of the cleaning unit 120 so asto detect an obstacle or feature in front of the robot so that thecleaning unit 120 positioned at the forefront of the autonomous mobilerobot 100 does not hit the obstacle.

The sensing unit 130 may be configured to perform other additionalsensing functions.

By way of example, the sensing unit 130 may include a camera 131 foracquiring surrounding images. The camera 131 may include a lens and animage sensor. The camera 131 may convert a surrounding image of thecleaner main body 110 into an electrical signal that can be processed bythe control unit. For example, the camera 131 may transmit an electricalsignal corresponding to an upward image to the control unit. Theelectrical signal corresponding to the upward image may be used by thecontrol unit to detect the position of the cleaner main body 110.

In addition, the sensing unit 130 may detect obstacles such as walls,furniture, and cliffs on a traveling surface or a traveling path of theautonomous mobile robot 100. Also, the sensing unit 130 may sensepresence of a docking device that performs battery charging. Also, thesensing unit 130 may detect ceiling information so as to map a travelingarea or a cleaning area of the autonomous mobile robot 100.

The cleaner main body 110 may include a dust container 140 detachablycoupled thereto for separating and collecting dust from sucked air.

The dust container 140 may include a dust container cover 150 which maycover the dust container 140. In an embodiment, the dust container cover150 may be coupled to the cleaner main body 110 by a hinge to berotatable. The dust container cover 150 may be fixed to the dustcontainer 140 or the cleaner main body 110 to keep covering an uppersurface of the dust container 140. The dust container 140 may beprevented from being separated from the cleaner main body 110 by thedust container cover 150 when the dust container cover 150 is disposedto cover the upper surface of the dust container 140.

A part of the dust container 140 may be accommodated in a dust containeraccommodating portion and another part of the dust container 140 mayprotrude toward the rear of the cleaner main body 110 (i.e., a reversedirection R opposite to a forward direction F).

The dust container 140 is provided with an inlet through which aircontaining dust may be introduced and an outlet through which airseparated from dust may be discharged. The inlet and the outlet maycommunicate with each other through an opening 155 formed through aninner wall of the cleaner main body 110 when the dust container 140 ismounted on the cleaner main body 110. Thus, an intake passage and anexhaust passage inside the cleaner main body 110 may be formed.

According to such connection, air containing dust introduced through thecleaning unit 120 may flow into the dust container 140 through theintake passage inside the cleaner main body 110 and the air may beseparated from the dust while passing through a filter and cyclone ofthe dust container 140. The separated dust may be collected in the dustcontainer 140, and the air may be discharged from the dust container 140and may flow along the exhaust passage inside the cleaner main body 110so as to be externally exhausted through an exhaust port.

Hereinafter, an embodiment related to the components of the autonomousmobile robot 100 will be described with reference to FIG. 4.

An autonomous mobile robot 100 or a mobile robot according to anembodiment of the present disclosure may include a communication unit1100, an input unit 1200, a traveling unit 1300, a sensing unit 1400, anoutput unit 1500, a power supply unit 1600, a memory 1700, a controlunit 1800, and a cleaning unit 1900, or a combination thereof.

An autonomous mobile robot having greater or fewer components may beimplemented. Also, as described above, each of a plurality of autonomousmobile robots described in the present disclosure may include only someof components to be described below. Further, a plurality of autonomousmobile robots may include different components.

Hereinafter, each component will be described.

First, the power supply unit 1600 may include a battery that can becharged by an external commercial power supply, and may supply power tothe mobile robot. The power supply unit 1600 may supply driving force toeach of the components included in the mobile robot to supply operatingpower required for the mobile robot to travel or perform a specificfunction.

The control unit 1800 may detect a remaining amount of power (orremaining power level or battery level) of the battery. The control unit1800 may control the mobile robot to move to a charging base connectedto the external commercial power supply when the remaining power isinsufficient, so that the battery can be charged by receiving chargingcurrent from the charging base. The battery may be connected to abattery sensing portion so that a remaining power level and a chargingstate can be transmitted to the control unit 1800. The output unit 1500may display the remaining battery level under the control of the controlunit.

The battery may be located in a bottom portion of a center of theautonomous mobile robot, or may be located in either the left or rightside. In the latter case, the mobile robot may further include a balanceweight to eliminate weight bias of the battery.

The control unit 1800 may perform processing of information based on anartificial intelligence (AI) technology and may include one or moremodules that perform at least one of learning of information, inferenceof information, perception of information, and processing of naturallanguage.

The control unit 1800 may use a machine learning technology to performat least one of learning, inferring, or processing a large amount ofinformation (big data), such as information stored in the cleaner,environmental information around a mobile terminal, information storedin an external storage capable of performing communication, and thelike. The control unit 1800 may control the cleaner to predict (orinfer) at least one executable operation and execute an operation havingthe highest feasibility among the predicted at least one executableoperation, by using the information learned using the machine learningtechnology.

Machine learning technology is a technology that may collect and learn alarge amount of information based on at least one algorithm, and judgeand predict information based on the learned information. The learningof information is an operation that may grasp characteristics, rules,and judgment criteria of information, quantify relationship betweeninformation and information, and predict new data using a quantifiedpattern.

The at least one algorithm used by the machine learning technology maybe a statistical based algorithm, for example, a decision tree that usesa tree structure type as a prediction model, an artificial neuralnetwork copying neural network architecture and functions, geneticprogramming based on biological evolutionary algorithms, clustering todistribute observed examples into subsets of clusters, Monte Carlomethod to compute function values through randomly extracted randomnumbers from probability, or the like.

As a field of machine learning technology, deep learning is a techniquethat may perform at least one of learning, judging, or processing ofinformation using an Artificial Neural Network (ANN) or a Deep NeuronNetwork (DNN) algorithm. Such DNN may have an architecture in whichlayers are connected to transfer data between layers. This deep learningtechnology may allow learning of a large amount of information throughthe DNN using a graphic processing unit (GPU) optimized for parallelcomputing.

The control unit 1800 may use training data stored in an external serveror memory, and may include a learning engine mounted to detectcharacteristics for recognizing a predetermined object. Thecharacteristics for recognizing the object may include a size, shape andshade of the object.

Specifically, when the control unit 1800 inputs a part of imagesacquired through the camera provided on the cleaner into the learningengine, the learning engine may recognize at least one object ororganism included in the input images.

When the learning engine is applied to traveling of the cleaner, thecontrol unit 1800 can recognize whether or not an obstacle such as achair leg, a fan, and a specific shape of balcony gap, which obstructthe running of the cleaner, exists around the cleaner. This may resultin enhancing efficiency and reliability of the traveling of the cleaner.

On the other hand, the learning engine may be mounted on the controlunit 1800 or on an external server. When the learning engine is mountedon an external server, the control unit 1800 may control thecommunication unit 1100 to transmit at least one image to be analyzed,to the external server.

The external server may input the image transmitted from the cleanerinto the learning engine and thus recognize at least one object ororganism included in the image. In addition, the external server maytransmit information related to the recognition result back to thecleaner. In this case, the information related to the recognition resultmay include information related to the number of objects included in theimage to be analyzed and a name of each object.

On the other hand, the traveling unit 1300 may include a motor, andoperate the motor to bidirectionally rotate left and right main wheels,so that the main body can rotate or move. The left and right main wheelsmay be independently moved. The traveling unit 1300 may advance the mainbody of the mobile robot forward, backward, left, right, curvedly, or inplace.

On the other hand, the input unit 1200 may receive various controlcommands for the autonomous mobile robot from the user. The input unit1200 may include one or more buttons, for example, the input unit 1200may include an OK button, a setting button, and the like. The OK buttonmay be a button for receiving a command for confirming detectioninformation, obstacle information, position information, and mapinformation from the user, and the setting button may be a button forreceiving a command for setting those information from the user.

In addition, the input unit 1200 may include an input reset button forcanceling a previous user input and receiving a new user input, a deletebutton for deleting a preset user input, a button for setting orchanging an operation mode, a button for receiving an input to return tothe charging base.

In addition, the input unit 1200 may be implemented as a hard key, asoft key, a touch pad, or the like and may be disposed on a top of themobile robot. For example, the input unit 1200 may implement a form of atouch screen together with the output unit 1500.

On the other hand, the output unit 1500 may be installed on a top of themobile robot. Of course, an installation location and an installationtype may vary. For example, the output unit 1500 may display a batterylevel state, a traveling mode or manner, or the like on a screen.

The output unit 1500 may output internal status information of themobile robot detected by the sensing unit 1400, for example, a currentstatus of each component included in the mobile robot. The output unit1500 may also display external status information detected by thesensing unit 1400, obstacle information, position information, mapinformation, and the like on the screen. The output unit 1500 may beconfigured as one device of a light emitting diode (LED), a liquidcrystal display (LCD), a plasma display panel, and an organic lightemitting diode (OLED).

The output unit 1500 may further include an audio output module foraudibly outputting information related to an operation of the mobilerobot executed by the control unit 1800 or an operation result. Forexample, the output unit 1500 may output warning sound to the outside inresponse to a warning signal generated by the control unit 1800.

In this case, the audio output module (not shown) may be means, such asa beeper, a speaker or the like for outputting sounds, and the outputunit 1500 may output sounds to the outside through the audio outputmodule using audio data or message data having a predetermined patternstored in the memory 1700.

Accordingly, the mobile robot according to an embodiment of the presentdisclosure can output environmental information related to a travelingarea through the output unit 1500 or output the same in an audiblemanner. According to another embodiment, the mobile robot may transmitmap information or environmental information to a terminal devicethrough the communication unit 1100 so that the terminal device outputsa screen to be output through the output unit 1500 or sounds.

The memory 1700 stores a control program for controlling or driving theautonomous mobile robot and data corresponding thereto. The memory 1700may store audio information, image information, obstacle information,position information, map information, and the like. Also, the memory1700 may store information related to a traveling pattern.

The memory 1700 may mainly use a nonvolatile memory. The non-volatilememory (NVM, NVRAM) may be a storage device that can continuously storeinformation even when power is not supplied. Examples of the storagedevice may include a ROM, a flash memory, a magnetic computer storagedevice (e.g., a hard disk, a diskette drive, a magnetic tape), anoptical disk drive, a magnetic RAM, a PRAM, and the like.

On the other hand, the sensing unit 1400 may include at least one of anexternal signal sensor, a front sensor, a cliff sensor, atwo-dimensional (2D) camera sensor, and a three-dimensional (3D) camerasensor.

The external signal sensor or external signal detection sensor may sensean external signal of a mobile robot. The external signal sensor may be,for example, an infrared ray (IR) sensor, an ultrasonic sensor, a radiofrequency (RF) sensor, or the like.

The mobile robot may detect a position and direction of the chargingbase by receiving a guidance signal generated by the charging base usingthe external signal sensor. The charging base may transmit a guidancesignal indicating a direction and distance so that the mobile robot canreturn thereto. The mobile robot may determine a current position andset a moving direction by receiving a signal transmitted from thecharging base, thereby returning to the charging base.

On the other hand, the front sensors or front detection sensors may beinstalled at a predetermined distance on the front of the mobile robot,specifically, along a circumferential surface of a side surface of themobile robot. The front sensor may be located on at least one sidesurface of the mobile robot to detect an obstacle in front of the mobilerobot. The front sensor may detect an object, especially an obstacle,located in a moving path of the mobile robot and transmit detectioninformation to the control unit 1800. For example, the front sensor maydetect protrusions in the moving path of the mobile robot, householdappliances, furniture, walls, wall corners, and the like, and maytransmit the information to the control unit 1800.

For example, the frontal sensor may be an infrared ray (IR) sensor, anultrasonic sensor, an RF sensor, a geomagnetic sensor, or the like, andthe mobile robot may use one type of sensor as the front sensor or twoor more types of sensors if necessary.

An ultrasonic sensor, for example, may generally be used to detect aremote obstacle. The ultrasonic sensor may include a transmitter and areceiver. The control unit 1800 may determine presence or non-presenceof an obstacle according to whether ultrasonic waves radiated from thetransmitter are reflected by an obstacle or the like and then receivedby the receiver, and calculate a distance from the obstacle using anultrasonic wave radiation time and an ultrasonic wave reception time.

Also, the control unit 1800 may detect information related to a size ofan obstacle by comparing ultrasonic waves radiated from the transmitterwith ultrasonic waves received by the receiver. For example, the controlunit 1800 may determine that the obstacle is larger in size when moreultrasonic waves are received in the receiver.

In one embodiment, a plurality (e.g., five) of ultrasonic sensors may beinstalled on side surfaces of the mobile robot at the front side alongan outer circumferential surface. The ultrasonic sensors may preferablybe installed on the front surface of the mobile robot in a manner thatthe transmitter and the receiver are alternately arranged.

The transmitters may be disposed at right and left sides while beingspaced apart from a front center of the main body or one transmitter orat least two transmitters may be disposed between the receivers so as toform a reception area of an ultrasonic signal reflected from an obstacleor the like. With this arrangement, the reception area may increasewhile reducing the number of sensors. A radiation angle of ultrasonicwaves may be maintained in a range to avoid affecting different signalsand prevent a crosstalk. Also, receiving sensitivity of the receiversmay be set differently.

In addition, the ultrasonic sensor may be installed upward by apredetermined angle so that the ultrasonic waves emitted from theultrasonic sensor are output upward. In this instance, the ultrasonicsensor may further include a predetermined blocking member to preventthe ultrasonic waves from being radiated downward.

On the other hand, as described above, the front sensor may beimplemented by using two or more types of sensors together, and thus thefront sensor may use any one of an IR sensor, an ultrasonic sensor, anRF sensor and the like.

For example, the front sensor may include an IR sensor as anothersensor, in addition to the ultrasonic sensor.

The IR sensor may be installed on an outer circumferential surface ofthe mobile robot together with the ultrasonic sensor. The IR sensor mayalso detect an obstacle existing on a front or side of the mobile robotand transmit obstacle information to the control unit 1800. For example,the IR sensor may detect a protrusion, a household fixture, furniture, awall, a wall edge, and the like, present in the moving path of themobile robot, and may transmit detection information to the control unit1800. Therefore, the mobile robot can move within a specific areawithout collision with an obstacle.

On the other hand, a cliff sensor (or cliff detection sensor) may detectan obstacle on the floor supporting the main body of the mobile robot bymainly using various types of optical sensors.

The cliff sensor may also be installed on a rear surface of the mobilerobot on the floor, but may be installed on a different positiondepending on a type of the mobile robot. The cliff sensor may be locatedon the rear surface of the mobile robot and may detect an obstacle onthe floor. The cliff sensor may be an IR sensor, an ultrasonic sensor,an RF sensor, a Position Sensitive Detector (PSD) sensor, and the like,which may include a transmitter and a receiver, similar to the obstacledetection sensor.

For example, one of the cliff sensors may be installed on the front ofthe mobile robot, and two other cliff sensors may be installedrelatively behind.

For example, the cliff sensor may be a PSD sensor, but may alternativelybe configured by a plurality of different kinds of sensors.

The PSD sensor may detect a short/long distance location of incidentlight at one p-n junction using semiconductor surface resistance. ThePSD sensor may include a one-dimensional PSD sensor that detects lightonly in one axial direction, and a two-dimensional PSD sensor thatdetects a light position on a plane. Both of the PSD sensors may have apin photodiode structure. As a type of infrared sensor, the PSD sensormay use infrared rays. The PSD sensor may emit infrared ray, and maymeasure a distance by calculating an angle of the infrared ray reflectedand returned from an obstacle. The PSD sensor may calculate a distancefrom the obstacle by using the triangulation method.

The PSD sensor may include a light emitter that emits infrared rays toan obstacle and a light receiver that receives infrared rays that arereflected and returned from the obstacle, and may be configured as amodule type. When an obstacle is detected by using the PSD sensor, astable measurement value may be obtained irrespective of reflectivityand color difference of the obstacle.

The control unit 1800 may measure an infrared ray angle between a lightsignal of infrared ray emitted by the cliff detection sensor toward theground and a reflection signal reflected and received from an obstacle,so as to detect a cliff and analyze a depth of the cliff.

Meanwhile, the control unit 1800 may determine whether to pass a cliffor not according to a ground state of the detected cliff by using thecliff detection sensor, and decide whether to pass the cliff or notaccording to the determination result. For example, the control unit1800 may determine presence or non-presence of a cliff and a depth ofthe cliff through the cliff sensor, and then allow the mobile robot topass through the cliff only when a reflection signal is detected throughthe cliff sensor.

As another example, the control unit 1800 may also determine lifting ofthe mobile robot using the cliff sensor.

On the other hand, the two-dimensional camera sensor may be provided onone surface of the mobile robot to acquire image information related tothe surroundings of the main body during movement.

An optical flow sensor may convert a lower image input from an imagesensor provided in the sensor to generate image data of a predeterminedformat. The generated image data may be stored in the memory 1700.

Also, at least one light source may be installed adjacent to the opticalflow sensor. The at least one light source may emit light to apredetermined area of the floor, which may be captured by the imagesensor. When the mobile robot moves in a specific area along the floorsurface, a certain distance may be maintained between the image sensorand the floor surface when the floor surface is flat. On the other hand,when the mobile robot moves on a floor surface which is not flat, theimage sensor and the floor surface may be spaced apart from each otherby a predetermined distance due to an unevenness and an obstacle on thefloor surface. The at least one light source may be controlled by thecontrol unit 1800 to adjust an amount of light to be emitted. The lightsource may be a light emitting device, for example, a light emittingdiode (LED), which is capable of adjusting an amount of light.

The control unit 1800 may detect a position of the mobile robotirrespective of slippage of the mobile robot, using the optical flowsensor. The control unit 1800 may compare and analyze image datacaptured by the optical flow sensor according to time to calculate amoving distance and a moving direction, and calculate a position of themobile robot based on the calculated moving distance and movingdirection. By using the image information regarding the lower side ofthe mobile robot captured by the image sensor, the control unit 1800 mayperform correction that is robust against slippage with respect to theposition of the mobile robot calculated by another member.

The three-dimensional (3D) camera sensor may be attached to one surfaceor a part of the main body of the mobile robot to generate 3D coordinateinformation related to surroundings of the main body.

The 3D camera sensor may be a 3D depth camera that calculates aremote/near distance between the mobile robot and an object to becaptured.

The 3D camera sensor may capture 2D images related to surroundings ofthe main body, and generate a plurality of 3D coordinate informationcorresponding to the captured 2D images.

In one embodiment, the 3D camera sensor may be configured in astereoscopic vision type which may include two or more cameras foracquiring 2D images, and merge at least two images acquired by the twoor more cameras to generate a 3D coordinate information.

The 3D camera sensor according to the embodiment may include a firstpattern irradiating portion for downwardly irradiating light of a firstpattern toward the front of the main body, a second pattern irradiatingportion for upwardly irradiating light of a second pattern toward thefront of the main body, and an image acquiring portion for acquiring afront image of the main body. Thus, the image acquiring portion mayacquire an image of an area where the light of the first pattern and thelight of the second pattern are incident.

In another embodiment, the 3D camera sensor may include an infraredpattern irradiating portion for irradiating an infrared pattern, inaddition to a single camera, and capture a shape that the infraredpattern irradiated from the infrared pattern irradiating portion isprojected onto an object to be captured, thereby measuring a distancebetween the 3D camera sensor and the object to be captured. The 3Dcamera sensor may be an IR type 3D camera sensor.

In another embodiment, the 3D camera sensor may include a light emittingportion for emitting light, in addition to a single camera. The 3Dcamera sensor may receive a part of laser light (or laser beam), whichis emitted from the light emitting portion and reflected from an objectto be captured, and analyze the received light, thereby measuring adistance between the 3D camera sensor and the object to be captured. The3D camera sensor may be a time-of-flight (TOF) type 3D camera sensor.

The laser of the 3D camera sensor may be configured to irradiate a laserbeam extending in at least one direction. In one example, the 3D camerasensor may be provided with first and second lasers. The first laser mayirradiate linear laser beams intersecting each other, and the secondlaser may irradiate single linear laser beam. According to this, thelowermost laser may be used to detect an obstacle on a bottom, theuppermost laser may be used to detect an obstacle on a top, and anintermediate laser between the lowermost laser and the uppermost lasermay be used to detect an obstacle at a middle portion.

On the other hand, the communication unit 1100 may be connected to aterminal device and/or another device (also referred to as “homeappliance” herein) through one of wired, wireless and satellitecommunication methods, so as to transmit and receive signals and data.

The communication unit 1100 may transmit and receive data with anotherdevice located in a specific area. In this case, the another device maybe any device if it can transmit and receive data through a network. Forexample, the another device may be an air conditioner, a heating device,an air purifier, a lamp, a TV, a vehicle, and the like. The anotherdevice may also be a device for controlling a door, a window, a watersupply valve, a gas valve, or the like. The another device may also be asensor for detecting temperature, humidity, air pressure, gas, or thelike.

Further, the communication unit 1100 may communicate with anotherautonomous mobile robot 100 located in a specific area or within apredetermined range.

Referring to FIGS. 5A and 5B, a first autonomous mobile robot 100 a anda second autonomous mobile robot 100 b may exchange data with each otherthrough a network communication 50. In addition, the first autonomousmobile robot 100 a and/or the second autonomous mobile robot 100 b mayperform a cleaning related operation or a corresponding operation by acontrol command received from a terminal 300 through the networkcommunication 50 or other communication.

Although not shown, the plurality of autonomous mobile robots 100 a and100 b may perform communication with the terminal 300 through a firstnetwork communication and perform communication with each other througha second network communication.

The network communication 50 may refer to short-range communicationusing at least one of wireless communication technologies, such as awireless LAN (WLAN), a wireless personal area network (WPAN), a wirelessfidelity (Wi-Fi) Wi-Fi direct, Digital Living Network Alliance (DLNA),Wireless Broadband (WiBro), World Interoperability for Microwave Access(WiMAX), Zigbee, Z-wave, Blue-Tooth, Radio Frequency Identification(RFID), Infrared Data Association (IrDA), Ultrawide-Band (UWB), WirelessUniversal Serial Bus (USB), and the like.

The network communication 50 may vary depending on a communication modeof the autonomous mobile robots desired to communicate with each other.

In FIG. 5A, the first autonomous mobile robot 100 a and/or the secondautonomous mobile robot 100 b may provide information sensed by therespective sensing units thereof to the terminal 300 through the networkcommunication 50. The terminal 300 may also transmit a control commandgenerated based on the received information to the first autonomousmobile robot 100 a and/or the second autonomous mobile robot 100 b viathe network communication 50.

In FIG. 5A, the communication unit of the first autonomous mobile robot100 a and the communication unit of the second autonomous mobile robot100 b may also directly communicate with each other or indirectlycommunicate with each other via another router (not shown), to recognizeinformation related to a traveling state and positions of counterparts.

In one example, the second autonomous mobile robot 100 b may perform atraveling operation and a cleaning operation according to a controlcommand received from the first autonomous mobile robot 100 a. In thiscase, the first autonomous mobile robot 100 a may operate as a mastercleaner and the second autonomous mobile robot 100 b may operate as aslave cleaner. Alternatively, the second autonomous mobile robot 100 bmay follow the first autonomous mobile robot 100 a. In some cases, thefirst autonomous mobile robot 100 a and the second autonomous mobilerobot 100 b may collaborate with each other.

Hereinafter, a system including a plurality of cleaners 100 a and 100 bperforming autonomous traveling according to an embodiment of thepresent disclosure will be described with reference to FIG. 5B.

As illustrated in FIG. 5B, a cleaning system according to an embodimentof the present disclosure may include a plurality of cleaners 100 a and100 b performing autonomous traveling, a network 50, a server 500, and aplurality of terminals 300 a and 300 b.

The plurality of cleaners 100 a and 100 b, the network 50 and at leastone terminal 300 a may be disposed in a building 10 while anotherterminal 300 b and the server 500 may be located outside the building10.

The plurality of cleaners 100 a and 100 b may be cleaners that performcleaning while traveling by themselves, and may perform autonomoustraveling and autonomous cleaning. Each of the plurality of cleaners 100a and 100 b may include a communication unit 1100, in addition to thetraveling function and the cleaning function.

The plurality of cleaners 100 a and 100 b, the server 500 and theplurality of terminals 300 a and 300 b may be connected together throughthe network 50 to exchange data. To this end, although not shown, awireless router such as an access point (AP) device and the like mayfurther be provided. In this case, the terminal 300 a located in thebuilding (internal network) 10 may access at least one of the pluralityof cleaners 100 a and 100 b through the AP device so as to performmonitoring, remote control and the like with respect to the cleaner.Also, the terminal 300 b located in an external network may access atleast one of the plurality of cleaners 100 a and 100 b through the APdevice, to perform monitoring, remote control and the like with respectto the cleaner.

The server 500 may be wirelessly connected through the terminal 300 b.Alternatively, the server 500 may be connected to at least one of theplurality of cleaners 100 a and 100 b without passing through the mobileterminal 300 b.

The server 500 may include a programmable processor and may includevarious algorithms. By way of example, the server 500 may includealgorithms for performing machine learning and/or data mining. As anexample, the server 500 may include a speech recognition algorithm. Inthis case, when receiving voice data, the received voice data may beoutput by being converted into data in a text format.

The server 500 may store firmware information, operation information(course information and the like) related to the plurality of cleaners100 a and 100 b, and may register product information regarding theplurality of cleaners 100 a and 100 b. For example, the server 500 maybe a server operated by a cleaner manufacturer or a server operated byan open application store operator.

In another example, the server 500 may be a home server that is providedin the internal network 10 and stores status information regarding thehome appliances or stores contents shared by the home appliances. If theserver 500 is a home server, information related to foreign substances,for example, foreign substance images and the like may be stored.

Meanwhile, the plurality of cleaners 100 a and 100 b may be directlyconnected to each other wirelessly via Zigbee, Z-wave, Blue-Tooth,Ultra-wide band, and the like. In this case, the plurality of cleaners100 a and 100 b may exchange position information and travelinginformation with each other.

Any one of the plurality of cleaners 100 a and 100 b may be a mastercleaner 100 a and another may be a slave cleaner 100 b.

In this case, the first mobile robot 100 a may control traveling andcleaning of the second mobile robot 100 b. In addition, the secondmobile robot 100 b may perform traveling and cleaning while followingthe first mobile robot 100 a. In some cases, the second mobile robot 100b may perform traveling and cleaning while following the first mobilerobot 100 a and maintaining a proper distance from the first mobilerobot 100 a.

Referring to FIG. 5C, the first mobile robot 100 a may control thesecond mobile robot 100 b such that the second mobile robot 100 b mayfollow the first mobile robot 100 a.

To this end, the first mobile robot 100 a and the second mobile robot100 b may be present in a specific area where they can communicate witheach other, and the second mobile robot 100 b may recognize at least arelative position of the first mobile robot 100 a.

For example, the communication unit of the first mobile robot 100 a andthe communication unit of the second mobile robot 100 b may exchange IRsignals, ultrasonic signals, carrier frequencies, impulse signals, andthe like, and may analyze them through triangulation, so as to calculatemovement displacements of the first mobile robot 100 a and the secondmobile robot 100 b, thereby recognizing relative positions of the firstmobile robot 100 a and the second mobile robot 100 b. However, thepresent disclosure is not limited to this method, and one of the variouswireless communication technologies described above may be used torecognize the relative positions of the first mobile robot 100 a and thesecond mobile robot 100 b through triangulation or the like.

When the first mobile robot 100 a recognizes the relative position withthe second mobile robot 100 b, the second mobile robot 100 b may becontrolled based on map information stored in the first mobile robot 100a or map information stored in the server, the terminal or the like. Inaddition, the second mobile robot 100 b may share obstacle informationsensed by the first mobile robot 100 a. The second mobile robot 100 bmay perform an operation based on a control command (for example, acontrol command related to a traveling direction, a traveling speed, astop, etc.) received from the first mobile robot 100 a.

Specifically, the second mobile robot 100 b may perform cleaning whiletraveling along a traveling path of the first mobile robot 100 a.However, the traveling directions of the first mobile robot 100 a andthe second mobile robot 100 b may not always coincide with each other.For example, when the first mobile robot 100 a moves or rotatesup/down/right/left, the second mobile robot 100 b may move or rotateup/down/right/left after a predetermined time, and thus currentadvancing directions of the first and second mobile robot 100 a and 100b may differ from each other.

Also, a traveling speed Va of the first mobile robot 100 a and atraveling speed Vb of the second mobile robot 100 b may be differentfrom each other.

The first mobile robot 100 a may control the traveling speed Vb of thesecond mobile robot 100 b to be varied in consideration of a distance atwhich the first mobile robot 100 a and the second mobile robot 100 b cancommunicate with each other. For example, if the first mobile robot 100a and the second mobile robot 100 b move away from each other by apredetermined distance or more, the first mobile robot 100 a may controlthe traveling speed Vb of the second mobile robot 100 b to be fasterthan before. On the other hand, when the first mobile robot 100 a andthe second mobile robot 100 b move close to each other by apredetermined distance or less, the first mobile robot 100 a may controlthe traveling speed Vb of the second mobile robot 100 b to be slowerthan before or control the second mobile robot 100 b to stop for apredetermined time. Accordingly, the second mobile robot 100 b mayperform cleaning while continuously following the first mobile robot 100a.

According to the present disclosure, the first mobile robot 100 a mayinclude reception sensors on front and rear sides, so that the controlunit of the first mobile robot 100 a may recognize a receiving directionof an optical signal received from the second mobile robot 100 b bydistinguishing the front and rear sides. To this end, a UWB module maybe provided at the rear of the first mobile robot 100 a and another UWBmodule or a plurality of optical sensors may be disposed at the front ofthe first mobile robot 100 a in a spacing manner. The first mobile robot100 a may recognize a receiving direction of an optical signal receivedfrom the second mobile robot 100 b and determine whether the secondmobile robot 100 b is coming from behind it or is located at the frontof it.

FIGS. 6A, 6B, and 6C are alternative embodiments of follow-up controlbetween the first mobile robot and the second mobile robot in accordancewith the present disclosure. Hereinafter, a follow-up control betweenthe first mobile robot and a mobile device will be described in detail.The follow-up control disclosed herein means that the mobile devicefollows the first mobile robot, or a movement path of the first mobilerobot.

Referring to FIG. 6A, the first mobile robot 100 a may control thefollow-up of a mobile device 200 by communicating with the mobile device200 instead of the second mobile robot.

In some embodiments, the mobile device 200 may be any electronic deviceprovided with a driving function without a clean function. For example,the mobile device 200 may include various types of home appliances orother electronic devices, such as a dehumidifier, a humidifier, an airpurifier, an air conditioner, a smart TV, an artificial intelligentspeaker, a digital photographing device, and the like.

In other embodiments, the mobile device 200 may be any device equippedwith a traveling function without a navigation function for detecting anobstacle by itself or traveling up to a predetermined destination.

The first mobile robot 100 a may be a mobile robot having both thenavigation function and the obstacle detection function and can controlthe follow-up of the mobile device 200. The first mobile robot 100 a maybe a dry-type cleaner or a wet-type cleaner.

The first mobile robot 100 a and the mobile device 200 may communicatewith each other through a network (not shown), but may directlycommunicate with each other.

The communication using the network may be communication using, forexample, WLAN, WPAN, Wi-Fi, Wi-Fi Direct, Digital Living NetworkAlliance (DLNA), Wireless Broadband (WiBro), World Interoperability forMicrowave Access (WiMAX), etc. The mutual direct communication may beperformed using, for example, UWB, Zigbee, Z-wave, Blue-Tooth, RFID, andInfrared Data Association (IrDA), and the like.

If the first mobile robot 100 a and the mobile device 200 are close toeach other, the mobile device 200 may be set to follow the first mobilerobot 100 a through a manipulation in the first mobile robot 100 a.

If the first mobile robot 100 a and the mobile device 200 are far awayfrom each other, although not shown, the mobile device 200 may be set tofollow the first mobile robot 100 a through a manipulation in anexternal terminal 300 (see FIG. 5A).

Specifically, follow-up relationship between the first mobile robot 100a and the mobile device 200 may be established through networkcommunication with the external terminal 300 (see FIG. 5A). The externalterminal 300 may be an electronic device capable of performing wired orwireless communication, and may be a tablet, a smart phone, a notebookcomputer, or the like. At least one application related to follow-upcontrol by the first mobile robot 100 a (hereinafter, ‘follow-up relatedapplication’) may be installed in the external terminal 300. The usermay execute the follow-up related application installed in the externalterminal 300 to select and register the mobile device 200 subjected tothe follow-up control by the first mobile robot 100 a. When the mobiledevice 200 subjected to the follow-up control is registered, theexternal terminal may recognize product information of the mobiledevice, and such product information may be provided to the first mobilerobot 100 a via the network.

The external terminal 300 may recognize the position of the first mobilerobot 100 a and the position of the registered mobile device 200 throughcommunication with the first mobile robot 100 a and the registeredmobile device 200. Afterwards, the first mobile robot 100 a may traveltoward the position of the registered mobile device 200 or theregistered mobile device 200 may travel toward the position of the firstmobile robot 100 a according to a control signal transmitted from theexternal terminal 300. When it is detected that the relative positionsof the first mobile robot 100 a and the registered mobile device 200 arewithin a predetermined following distance, the follow-up control for themobile device 200 by the first mobile robot 100 a may be started. Thefollow-up control may then be performed by direct communication betweenthe first mobile robot 100 a and the mobile device 200 without theintervention of the external terminal 300.

The setting of the follow-up control may be released by the operation ofthe external terminal 300 or automatically terminated as the firstmobile robot 100 a and the mobile device 200 move away from thepredetermined following distance.

The user may change, add, or remove the mobile device 200 to becontrolled by the first mobile robot 100 a by manipulating the firstmobile robot 100 a or the external terminal 300. For example, referringto FIG. 6B, the first mobile robot 100 a may perform the follow-upcontrol for at least one mobile device 200 of another cleaner 200 a or100 b, an air purifier 200 b, a humidifier 200 c, and a dehumidifier 200d.

Generally, since the mobile device 200 may be different from the firstmobile robot 100 a in its function, product size, and traveling ability,it may be difficult for the mobile device 200 to follow the movementpath of the mobile robot 100 a as it is. For example, there may be anexceptional situation in which it may be difficult for the mobile device200 to follow the movement path of the first mobile robot 100 aaccording to a geographical characteristic of a space, a size of anobstacle, and the like. In consideration of such an exceptionalsituation, the mobile device 200 may travel or wait by omitting a partof the movement path even if it recognizes the movement path of thefirst mobile robot 100 a. To this end, the first mobile robot 100 a maydetect whether or not the exceptional situation occurs, and control themobile device 200 to store data corresponding to the movement path ofthe first mobile robot 100 a in a memory or the like. Then, depending onsituations, the first mobile robot 100 a may control the mobile device200 to travel with deleting part of the stored data or to wait in astopped state.

FIG. 6C illustrates an example of a follow-up control between the firstmobile robot 100 a and the mobile device 200, for example, the aircleaner 200 b having a traveling function. The first mobile robot 100 aand the air purifier 200 b may include communication modules A and B fordetermining relative positions thereof, respectively. The communicationmodules A and B may be one of the modules for emitting and receiving anIR signal, an ultrasonic signal, a carrier frequency, or an impulsesignal. The recognition of the relative positions through thecommunication modules A and B has been described above in detail, so adescription thereof will be omitted. The air purifier 200 b may receivetraveling information corresponding to a traveling command (e.g.,changes in traveling including a traveling direction and a travelingspeed, traveling stop, etc.) from the first mobile robot 100 a, travelaccording to the received traveling information, and perform airpurification. Accordingly, the air purification may be performed in realtime with respect to a cleaning space in which the first mobile robot100 a operates. In addition, since the first mobile robot 100 a hasalready recognized the production information related to the mobiledevice 200, the first mobile robot 100 a may control the air purifier200 b to record the traveling information of the first mobile robot 100a, and travel with deleting part of the traveling information or wait ina stopped state.

Hereinafter, description will be given in more detail of a method inwhich a plurality of mobile robots determines relative positions toperform a following travel in accordance with one embodiment of thepresent disclosure, with reference to the accompanying drawings.

The first autonomous mobile robot 100 a of the present disclosure may bereferred to as a first mobile robot or a first mobile robot 100 a andthe second autonomous mobile robot 100 b may be referred to as a secondmobile robot or a second mobile robot 100 b.

Also, in the present disclosure, the first mobile robot 100 a may serveas a leading cleaner (or master cleaner) that travels in a directionahead of the second mobile robot 100 b, and the second mobile robot 100b may serve as a following cleaner (or slave cleaner) that follows thefirst mobile robot 100 a.

The first and second mobile robots 100 a and 100 b may perform travelingand cleaning in a following manner without a user's intervention.

In order for the second mobile robot 100 b to follow the first mobilerobot 100 a, the second mobile robot 100 b may determine or recognizethe relative position of the first mobile robot 100 a.

The present disclosure provides a method of estimating a highly accuraterelative position using a minimum number of components, which may resultin cost savings.

Hereinafter, a method of determining the relative position of the firstmobile robot 100 a by the second mobile robot 100 b by using only theleast components will be described in more detail, with reference to theaccompanying drawings.

FIGS. 7A and 7B are conceptual views illustrating a plurality ofautonomous mobile robots in accordance with one embodiment of thepresent disclosure.

First, referring to FIG. 7A, the first mobile robot 100 a of the presentdisclosure may include one antenna 710 a provided on one point of thefirst mobile robot (main body) and configured to transmit and receivesignals.

The one antenna 710 a may be configured to transmit and receive varioussignals. For example, the antenna 710 a may be configured to transmitand receive at least one of an Ultra-WideBand (UWB) signal, a signaloutput by one of wireless communication technologies (e.g., one ofZigbee, Z-wave, Blue-tooth, and UWB), an infrared signal, a lasersignal, and an ultrasonic signal.

The antenna 710 a may be connected to a module (or a sensor) thattransmits and/or receives (or generates) a signal, and may play a roleof transmitting the signal generated in the module (or sensor) orreceiving a signal transmitted from outside.

The module (or sensor) that transmits/receives (or generates) the signalmay include various communication modules included in the communicationunit 1100 or may include various sensors included in the sensing unit1400.

The first mobile robot 100 a may include a UWB module 700 a fortransmitting and receiving (or generating) ultra-wideband (UWB) signals.The UWB module 700 a included in the first mobile robot 100 a may be aUWB tag 700 a.

The one antenna 710 a may be electrically connected to the UWB tag 700 aand may output a signal (e.g., UWB signal) under the control of the UWBtag 700 a.

The first mobile robot 100 a may include at least one antenna in one UWBtag 700 a. In certain embodiments, for cost reduction, only one antenna710 a may be (electrically) connected to one UWB tag 700 a although itshould be noted that the present disclosure is not limited thereto.

Hereinafter, the one antenna 710 a will be referred to as an antenna 710a of the first mobile robot.

The one point of the first mobile robot 100 a on which the antenna 710 aof the first mobile robot is disposed may vary, and may be predeterminedat the time of product manufacture or determined/changed by the user.

As one example, as illustrated in FIG. 7A, the one point of the firstmobile robot 100 a on which the antenna 710 a of the first mobile robotis located may be a center c (a central portion, a central area, orcenter point) of the first mobile robot.

That is, the antenna 710 a of the first mobile robot 100 a may bedisposed (located) at the center c of the first mobile robot 100 a.

The antenna 710 a of the first mobile robot may be provided on thesurface of the first mobile robot 100 a (main body) or may be disposedin the interior (inner space) of the first mobile robot 100 a.

For example, the antenna 710 a of the first mobile robot 100 a may bedisposed on a center point of an upper surface of the first mobile robot100 a.

As another example, the antenna 710 a of the first mobile robot 100 amay be disposed at the center c inside the first mobile robot 100 a.

Even if the antenna 710 a of the first mobile robot is provided insidethe first mobile robot 100 a, a signal transmitted/received through theantenna 710 a of the first mobile robot may pass through the main bodyof the first mobile robot 100 a. Therefore, the antenna 710 a of thefirst mobile robot 100 may transmit and receive the signal through themain body of the first mobile robot 100 a.

According to the present disclosure, as the antenna 710 a of the firstmobile robot is disposed at the center (or central portion) c of thefirst mobile robot, an error rate may be lowered when the second mobilerobot determines the relative position of the first mobile robot.

This is because degrees of intensities or qualities of signals that aredeteriorated (lowered or attenuated) may be the same/similar, which mayresult from that distances by which signals output from the antenna 710a of the first mobile robot pass through the main body are all the samewhen the antenna 710 a of the first mobile robot is disposed at thecenter c of the first mobile robot.

As another example, as illustrated in FIG. 7B, the one point of thefirst mobile robot 100 a on which the antenna 710 a of the first mobilerobot is located may be a rear area r1 of the first mobile robot (or arear side on the main body of the first mobile robot, one point locatedon the rear of the first mobile robot, or the like).

According to the present disclosure, the first mobile robot can smoothlytransmit and receive signals to and from the second mobile robot whichmay be traveling behind the first mobile robot by arranging the antenna710 a of the first mobile robot in the rear area r1 of the first mobilerobot.

Even though the antenna 710 a of the first mobile robot is disposed onan arbitrary point, the module (or sensor) (e.g., the UWB tag 700 a)which transmits and receives signals to and from the antenna 710 a ofthe first mobile robot (or generates the signals) may be electricallyconnected to the antenna 710 a of the first mobile robot.

The present disclosure may be configured to output a signal generated inthe module (or sensor) (e.g., the UWB tag 700 a) through the antenna 710a of the first mobile robot and receive a signal received from outsidethrough the antenna 710 a of the first mobile robot so as to transfer tothe module (or sensor).

The first mobile robot 100 a may be configured to output (send) orreceive signals in all directions through the antenna 710 a of the firstmobile robot. Also, the first mobile robot 100 a may be configured tooutput or receive signals only in an arbitrary area (or an arbitrarydirection) through the antenna 710 a of the first mobile robot.

On the other hand, the second mobile robot 100 b of the presentdisclosure, as illustrated in FIGS. 7A and 7B, may include a firstantenna 710 b and a second antenna 720 b provided on the main body 100 band disposed on front areas (or the front side) f1 and f2 of the mainbody 100 b so as to transmit and receive signals to and from the antenna710 a of the first mobile robot.

The first and second antennas 710 b and 720 b may be provided on themain body of the second mobile robot 100 b (or the second mobile robotmain body 100 b). The main body 100 b may include a front area and arear area. The first and second antennas 710 b and 720 b may be providedon the second mobile robot main body 100 b and may be located on a frontarea of the main body 100 b (or at the front area on the main body 100b).

The front area may refer to one area on the second mobile robot mainbody 100 b and may refer to a front area of an entire area of the secondmobile robot body 100 b. The entire area of the main body 100 b mayinclude a front area and a rear area.

The front area may correspond to an area located at a front side ofareas (front area and rear area) of the second mobile robot main body100 b, which are divided by a reference line penetrating through thecenter of the second mobile robot main body 100 b and extending in leftand right directions.

Also, the front area may correspond to an area located at a front sideamong four areas of the second mobile robot main body 100 b if thesecond mobile robot main body 100 b is divided into an area located atthe front, an area at the rear, an area located at the left and an arealocated at the right (i.e., the four areas).

The first antenna 710 b and the second antenna 720 b, as illustrated inFIGS. 7A and 7B, may be provided on the second mobile robot main body100 b and may be located at two arbitrary points on the front (or frontarea) of the second mobile robot main body 100 b.

For example, the first antenna 710 b and the second antenna 720 b may bedisposed areas f1 and f2 located at the front side of the second mobilerobot main body on a boundary where an upper surface and a side surfaceof the second mobile robot main body 100 b meet each other.

As another example, the first antenna 710 b and the second antenna 720 bmay be disposed on an area, facing the front, of the side surface of thesecond mobile robot main body 100 b.

As another example, the first antenna 710 b and the second antenna 720 bmay be disposed on an area located on the front of the upper surface ofthe second mobile robot main body 100 b.

The first antenna 710 b and the second antenna 720 b may be disposed tohave a predetermined distance d. For example, the first antenna 710 band the second antenna 720 b may be disposed adjacent to each other witha predetermined distance d.

Also, the first antenna 710 b and the second antenna 720 b may bedisposed to be symmetric with each other in right and left directionswith respect to the front of the second mobile robot main body 100 b.

As illustrated in FIGS. 7A and 7B, the first antenna 710 b and thesecond antenna 720 b may be disposed to be symmetric with each other inright and left directions with respect to a reference line whichpenetrates through the center of the second mobile robot main body 100 band extends toward the front side.

The first antenna 710 b and the second antenna 720 b may be disposedsymmetrically to have the same distance from the reference line, and maybe disposed so that a distance therebetween is a predetermined distanced.

The predetermined distance d may have a significantly shorter value thana width of the second mobile robot main body 100 b. For example, thefirst antenna 710 b and the second antenna 720 b may be disposed to havea gap of several centimeters, and may also be disposed on areas adjacentto each other.

However, the present disclosure is not limited to this, and the firstantenna 710 b and the second antenna 720 b may alternatively be disposedon one of the rear area, the left area or the right area of the mainbody of the second mobile robot 100 b.

The first antenna 710 b and the second antenna 720 b may also bedisposed on different areas of the second mobile robot main body 100 b(e.g., the first antenna 710 b may be disposed on the front area and thesecond antenna 720 b may be disposed on the rear area).

In the present disclosure, in some embodiments, both the first antenna710 b and the second antenna 720 b may be disposed on the front areasf1, f2. However, the configuration described herein may also beequally/similarly applied even to a case where the first and secondantennas 710 b and 720 b are disposed on any one of the rear, left, andright areas, or on different areas.

According to the present disclosure, by arranging the first antenna 710b and the second antenna 720 b on the front area of the second mobilerobot main body 100 b, a signal received from the first mobile robot 100a that is traveling ahead of the second mobile robot 100 b may bereceived directly without passing through the second mobile robot mainbody 100 b.

In this case, the signal may be received through the first antenna 710 band the second antenna 710 b, not via the second mobile robot main body100 b, which may result in preventing attenuation or lowering ofintensity and quality of the signal.

The first antenna 710 b and the second antenna 720 b, as described inrelation to the antenna 710 a of the first mobile robot, may beelectrically connected to the module (or sensor) provided in the secondmobile robot 100 b for generating (or transmitting and receiving) asignal.

The first antenna 710 b and the second antenna 720 b may be configuredto transmit and receive signals to and from the antenna 710 a of thefirst mobile robot.

The first antenna 710 b and the second antenna 720 b may be configuredto transmit and receive various signals, for example, a UWB signal, aninfrared signal, a laser signal, and an ultrasonic signal.

The first antenna 710 b and the second antenna 720 b may be configuredto transmit and receive various signals. For example, the antenna 710 amay be configured to transmit and receive at least one of anUltra-WideBand (UWB) signal, a signal output by one of wirelesscommunication technologies (e.g., one of Zigbee, Z-wave, Blue-tooth, andUWB), an infrared signal, a laser signal, and an ultrasonic signal.

The module (or sensor) that transmits/receives (or generates) the signalmay include various communication modules included in the communicationunit 1100 or may include various sensors included in the sensing unit1400.

The second mobile robot 100 b may include, for example, a UWB module 700b that transmits/receives a UWB signal. The UWB module 700 b included inthe second mobile robot 100 b may be a UWB anchor 700 b.

The first antenna 710 b and the second antenna 720 b may be electricallyconnected to the UWB anchor 700 b and output a signal (e.g., UWB signal)under the control of the UWB anchor 700 b.

The second mobile robot 100 b may include one UWB anchor 700 b and thefirst antenna 710 b and the second antenna 720 b may be electricallyconnected to the one UWB anchor 700 b.

The UWB anchor 700 b included in the second mobile robot 100 b mayinclude three or more antennas. In certain embodiments, for costreduction, only two antennas 710 b and 720 b may be (electrically)connected to the one UWB anchor 700 b although the present disclosure isnot limited thereto.

As aforementioned, signals transmitted and received between the antenna710 a of the first mobile robot and the first antenna 710 b and thesecond antenna 720 b of the second mobile robot 100 b may pass throughthe main body of the first mobile robot 100 a and the main body of thesecond mobile robot 100 b.

For example, when the signal is a UWB signal, the signal may have a highfrequency and thus may have a characteristic of advancing through anobject.

The second mobile robot 100 b according to the present disclosure may beconfigured so that a signal output from the antenna 710 a of the firstmobile robot can pass (penetrate) therethrough. For example, the firstantenna 710 b and the second antenna 720 b may receive a UWB signaloutput from the antenna 710 a of the first mobile robot through the mainbody of the second mobile robot 100 b.

For example, when the first antenna 710 b and the second antenna 720 bare located on a front area of the main body of the second mobile robot100 b (for example, on a forefront point, on a boundary where an uppersurface and a side surface meet, on a front area of the side surface, oron a forefront area of the upper surface), the first antenna 710 b andthe second antenna 720 b may be configured to receive signals, which maybe transmitted in all directions except for the front of the main bodyof the second mobile robot 100 b, through the main body of the secondmobile robot 100 b.

Intensity of the signal received by the first antenna 710 b and thesecond antenna 720 b may be reduced when the signal is received throughthe main body of the second mobile robot 100 b.

Intensity W1 of a signal received directly by the first antenna 710 band the second antenna 720 b, not through the second mobile robot (orthe second mobile robot main body) 100 b after being output from theantenna 710 a of the first mobile robot may be stronger than intensityW2 of a signal received by the first antenna 710 b and the secondantenna 720 b through the second mobile robot 100 b after being outputfrom the antenna 710 a of the first mobile robot (W1>W2).

This is because the signal may be attenuated while passing through themain body and thereby intensity or quality of the signal may bedeteriorated.

For example, the case where the signal is received directly by the firstantenna 710 b and the second antenna 720 b, not through the secondmobile robot 100 b after being output from the antenna 710 a of thefirst mobile robot, may correspond to a case where the first mobilerobot 100 a is located at the front of the second mobile robot 100 b andthe first antenna 710 b and the second antenna 720 b are arranged on thefront area of the second mobile robot (or the second mobile robot mainbody) 100 b.

For example, when the signal is output from the antenna 710 a of thefirst mobile robot and then received by the first antenna 710 b and thesecond antenna 720 b through the second mobile robot 100 b, the firstmobile robot 100 a may be located in a direction except for the front ofthe second mobile robot 100 b (e.g., in a left, right or rear directionof the second mobile robot), and the first antenna 710 b and the secondantenna 720 b may be arranged on the front area of the second mobilerobot 100 b.

The control unit 1800 of the second mobile robot 100 b may determine(decide) whether the signal output from the antenna 710 a of the firstmobile robot 100 a is received through the second mobile robot 100 b orwithout passing through the second mobile robot 100 b, on the basis ofintensity of the signal received by the first antenna 710 b and thesecond antenna 720 b.

The control unit 1800 of the second mobile robot 100 b may determinewhether the first mobile robot 100 a is located at the front or rear ofthe second mobile robot with respect to the front of the second mobilerobot 100 b, on the basis of the intensity of the signal received by thefirst and second antennas 710 b and 720 b.

The present disclosure also provides a plurality of autonomous mobilerobots that the second mobile robot 100 b may accurately determine arelative position of the first mobile robot 100 a using only twoantennas (receiving antennas) 710 b and 720 b, on the basis of intensityof a signal received through the first antenna 710 b and the secondantenna 720 b.

Hereinafter, description will be given of a method in which the secondmobile robot determines the relative position of the first mobile robotusing only two receiving antennas, with reference to the accompanyingdrawings.

FIG. 8 is a conceptual view illustrating a method of determining adistance between a first mobile robot and a second mobile robot usingUWB modules in accordance with one embodiment of the present disclosure.

Description given with reference to FIGS. 7A and 7B may be applied tothe embodiment of FIG. 8 in the same or similar manner.

The first mobile robot 100 a may include one antenna 710 a provided onone point of the first mobile robot and configured to transmit andreceive signals.

The second mobile robot 100 b may include a first antenna 710 b and asecond antenna 720 b which may be provided on the front area of the mainbody 100 b and configured to transmit and receive signals to and fromthe antenna of the first mobile robot.

The control unit 1800 of the second mobile robot 100 b may determine therelative position of the first mobile robot using the signal receivedthrough the first antenna 710 b and the second antenna 720 b.

First, the first mobile robot 100 a and the second mobile robot 100 b ofthe present disclosure may be provided with UWB modules 700 a and 700 b,respectively, for transmitting and receiving UWB signals transmitted andreceived through the antennas 710 a, 710 b and 720 b.

For example, the first mobile robot 100 a may include a UWB tag 700 athat transmits and receives a UWB signal, and the one antenna 710 a ofthe first mobile robot may be electrically connected to the UWB tag 700a.

The second mobile robot 100 b may include a UWB anchor 700 b thattransmits and receives the UWB signal and the first antenna 710 b andthe second antenna 720 b of the second mobile robot may be electricallyconnected to the UWB anchor 700 b.

The antenna 710 a of the first mobile robot and the first and secondantennas 710 b and 720 b of the second mobile robot may transmit andreceive signals (UWB signals) generated by the UWB tag 700 a and the UWBanchor 700 b.

For example, the UWB tag 700 a and the UWB anchor 700 b may transmit andreceive signals (UWB signals) through the antenna 710 a of the firstmobile robot and the first and second antennas 710 b and 720 b of thesecond mobile robot.

Hereinafter, description will be given of a method of measuring(determining, calculating) a distance between the antenna 710 a of thefirst mobile robot and the first antenna 710 b of the second mobilerobot, based on a signal transmitted and received between the UWB tag700 and the UWB anchor 700 b (or between the antenna 710 a connected tothe UWB tag 700 a and the first antenna 710 b connected to the UWBanchor).

The following description will be applied equally/similarly to a methodof measuring (determining) a distance between the antenna 710 a of thefirst mobile robot and the second antenna 720 b of the second mobilerobot.

The UWB modules (or UWB sensors) may be included in the communicationunits 1100 of the first mobile robot 100 a and the second mobile robot100 b. Because the UWB modules may be used to sense the relativepositions of the first mobile robot 100 a and the second mobile robot100 b, the UWB modules 700 a and 700 b may be included in the sensingunits 1400 of the first mobile robot 100 a and the second mobile robot100 b.

A UWB signal transmitted and received between the UWB tag 700 a and theUWB anchor 700 b may be smoothly transmitted and received within aspecific space. For example, the UWB signal may pass through the firstmobile robot 100 a and/or the second mobile robot 100 b.

Even if an obstacle is present between the first mobile robot 100 a andthe second mobile robot 100 b (or between the antenna 710 a of the firstmobile robot and the first antenna 710 b of the second mobile robot),when the first mobile robot 100 a and the second mobile robot 100 b arepresent within a specific space, transmission and reception of the UWBsignal may be performed, which may increase accuracy.

The first mobile robot and the second mobile robot of the presentdisclosure may measure a time during which a signal is transmitted andreceived between the UWB tag 700 a and the UWB anchor 700 b so as tocalculate (determine) a distance between the first mobile robot and thesecond mobile robot (or a distance between the antenna 710 a of thefirst mobile robot and the first antenna 710 b of the second mobilerobot).

In general, the UWB tag and the UWB anchor may be both UWB modules,which may be modules to transmit and receive UWB signals.

For example, the UWB module included in one robot 100 b for calculating(determining) a relative position of another mobile robot 100 a may bereferred to as a UWB anchor, and a UWB module included in the robot 100a whose relative position is to be recognized may be referred to as aUWB tag.

Each of the plurality of mobile robots 100 a and 100 b may include oneUWB sensor, or the first mobile robot 100 a may include a single UWBsensor, and the second mobile robot 100 b following the first mobilerobot 100 a may include a single UWB sensor and at least one antenna orat least two UWB sensors, so that the first mobile robot 100 a canmeasure distances to the second mobile robot 100 b at two different timepoints t1 and t2.

The UWB sensor of the first mobile robot 100 a and the UWB sensor of thesecond mobile robot 100 b may radiate UWB signals to each other, andmeasure a distance and relative speed using Time of Arrival (ToA) orTime of Flight (ToF) which is a time that the signal comes back by beingreflected from the robot. However, the present disclosure is not limitedto this, and may recognize the relative positions of the plurality ofmobile robots 100 a and 100 b using a Time Difference of Arrival (TDoA)or Angle of Arrival (AoA) positioning technique.

For example, as illustrated in FIG. 8, the control unit 1800 of thesecond mobile robot 100 b may control the UWB anchor 700 b to output afirst signal (Radio message 1) through at least one of the first antenna710 b and the second antenna 720 b.

The control unit 1800 of the second mobile robot 100 b may output thefirst signal from the UWB anchor 700 b through at least one of the firstantenna 710 b and the second antenna 720 b.

The first signal may be received in the UWB tag through the antenna 710a of the first mobile robot 100 a.

The control unit 1800 of the first mobile robot 100 a may control theUWB tag 700 a to output the second signal (Radio message 2) through theantenna 710 a of the first mobile robot 100 a, in response to thereception of the first signal.

The second signal may include information related to a delay timet_reply which may be calculated based on a time at which the firstmobile robot 100 a has received the first signal and a time at which thefirst mobile robot 100 a has output (transmitted) the second signal.

The control unit 1800 of the second mobile robot 100 b may receive thesecond signal through the UWB anchor 700 b (through the first antenna710 b of the second mobile robot 100 b).

The control unit of the second mobile robot 100 b may calculate(determine) a signal transmission time, namely, Time of Flight (ToF),between the antenna 710 a of the first mobile robot and the firstantenna 710 b of the second mobile robot using an output time t1 of thefirst signal, a received time t2 of the second signal in the firstantenna 710 b of the second mobile robot, and the delay time t_replyincluded in the second signal.

The signal transmission time (i.e., TOF) may refer to a time for whichthe signal (UWB signal) is transmitted from the antenna 710 a of thefirst mobile robot to the first antenna 710 b of the second mobile robot(or from the first antenna 710 b of the second mobile robot to theantenna 710 a of the first mobile robot).

The control unit 1800 of the second mobile robot 100 b may calculate adistance between the first mobile robot 100 a and the second mobilerobot 100 b (accurately, a distance between the antenna 100 a of thefirst mobile robot and the first antenna 710 b of the second mobilerobot), using the output time t1 of the first signal, the received timet2 of the second signal in the first antenna 710 b of the second mobilerobot, and the delay time t_reply included in the second signal. Here, cin FIG. 8 denotes speed of light.

For example, the control unit of the second mobile robot 100 b maycalculate (determine) the distance (first distance) between the firstantenna 710 a of the first mobile robot and the first antenna 710 b ofthe second mobile robot by multiplying the calculated TOF by the speedof light.

To this end, the control unit of the second mobile robot 100 b may alsocalculate (determine) the distance between the antenna 710 a of thefirst mobile robot and the second antenna 720 b of the second mobilerobot.

For example, the control unit of the second mobile robot 100 b maycalculate a signal transmission time, namely, Time of Flight (ToF′)between the antenna 710 a of the first mobile robot and the secondantenna 720 b of the second mobile robot, using the output time t1 ofthe first signal, a received time t2′ of the second signal in the secondantenna 720 b of the second mobile robot, and the delay time t_replyincluded in the second signal.

The signal transmission time (i.e., TOF) may refer to a time for whichthe signal (UWB signal) is transmitted from the antenna 710 a of thefirst mobile robot to the second antenna 720 b of the second mobilerobot (or from the second antenna 720 b of the second mobile robot tothe antenna 710 a of the first mobile robot).

The control unit 1800 of the second mobile robot 100 b may calculate thedistance between the first mobile robot 100 a and the second mobilerobot 100 b (accurately, the distance between the antenna 100 a of thefirst mobile robot and the second antenna 720 b of the second mobilerobot), using the output time t1 of the first signal, the received timet2′ of the second signal in the second antenna 720 b of the secondmobile robot, and the delay time t_reply included in the second signal.

For example, the control unit of the second mobile robot 100 b maycalculate (determine) the distance (second distance) between the antenna710 a of the first mobile robot and the second antenna 720 b of thesecond mobile robot by multiplying the calculated TOF′ by the speed oflight.

The control unit 1800 of the second mobile robot 100 b may measure eachtime t2 and t2′ at which the second signal is received in the firstantenna 710 b and the second antenna 720 b of the second mobile robot,in a state where the first antenna 710 b and the second antenna 720 b ofthe second mobile robot are activated at the same time.

Accordingly, the control unit 1800 of the second mobile robot 100 b maycalculate the first distance between the antenna 710 a of the firstmobile robot and the first antenna 710 b of the second mobile robot andthe second distance between the antenna 710 a of the first communicationsystem and the second antenna 720 b of the second mobile robot,respectively, on the basis of the time t1 at which the first signal isoutput through at least one of the first and second antennas 710 b and720 b, each time t2 and t2′ at which the second signal is received bythe first and second antennas 710 b and 720 b, and the delay timet_reply included in the second signal.

The control unit 1800 of the second mobile robot 100 b may alsosequentially calculate the first distance and the second distance bysequentially activating the first antenna 710 b and the second antenna720 b of the second mobile robot.

For example, the control unit 1800 of the second mobile robot 100 b maycalculate the first distance in a state in which the first antenna 710 bof the second mobile robot is activated and the second antenna 720 b isdeactivated.

Afterwards, when the first distance is calculated, the control unit 1800of the second mobile robot 100 b may calculate the second distance bydeactivating the first antenna 710 b and activating the second antenna720 b.

On the other hand, since only the two antennas 710 b and 720 b areprovided in the second mobile robot, the triangulation scheme may not beutilized.

The present disclosure may determine direction information (or angleinformation) related to the first mobile robot based on the forwarddirection of the second mobile robot, using an Angle of Arrival (AoA)positioning technique, through two UWB anchors (or two antennas).

Hereinafter, description will be given of a method of determining therelative positions of the first mobile robot 100 a and the second mobilerobot 100 b using an AoA positioning technique. In order to use the AoApositioning technique, each of the first mobile robot 100 a and thesecond mobile robot 100 b may be provided with one receiving antenna ora plurality of receiving antennas. The first mobile robot 100 a and thesecond mobile robot 100 b may determine their relative positions using adifference (or phase difference) of angles that the receiving antennasprovided in the robots, respectively, receive signals. To this end, eachof the first mobile robot 100 a and the second mobile robot 100 b may beable to sense an accurate signal direction coming from a receivingantenna array.

Since signals, for example, UWB signals, generated in the first mobilerobot 100 a and the second mobile robot 100 b, respectively, may bereceived only in specific directional antennas, they can determine(recognize) received angles of the signals. Under assumption thatpositions of the receiving antennas provided in the first mobile robot100 a and the second mobile robot 100 b are known, the relativepositions of the first mobile robot 100 a and the second mobile robot100 b may be calculated based on signal receiving directions of thereceiving antennas.

If one receiving antenna is installed, a 2D position may be calculatedin a space of a predetermined range. On the other hand, if at least tworeceiving antennas are installed, a 3D position may be determined. Inthe latter case, a distance d between the receiving antennas may be usedfor positioning in order to accurately determine a signal receivingdirection.

For example, one UWB tag (or one antenna) may be provided in the firstmobile robot 100 a, and at least two UWB anchors (or at least twoantennas) may be provided in the second mobile robot 100 b. The secondmobile robot 100 b may receive the UWB signal transmitted from the UWBtag of the first mobile robot 100 a through each of the at least two UWBanchors (or the at least two antennas).

Thereafter, the second mobile robot 100 b may determine positioninformation (or angle information) where the first mobile robot 100 a islocated with reference to a forward direction of the second mobile robot100 b, by using a phase difference between the UWB signals receivedthrough the at least two UWB anchors (at least two antennas) and adistance between the at least two UWB anchors (or at least twoantennas).

For example, the second mobile robot of the present disclosure mayextract distance information between the first mobile robot and thesecond mobile robot using the ToF scheme, and determine directioninformation (or angle information) in which the first mobile robot islocated with respect to the forward direction of the second mobile robot100 b using the AoA scheme. Further, the second mobile robot maydetermine the relative position of the first mobile robot using thedistance information and the angle information.

In addition, the present disclosure may determine the relative positionof the first mobile robot based on intensities of signals receivedthrough two antennas, even if the second mobile robot is provided withonly the two antennas 710 b and 720 b.

Hereinafter, description will be given in more detail of a method inwhich the second mobile robot determines the relative position of thefirst mobile robot using two antennas, with reference to theaccompanying drawings.

FIG. 9 is a flowchart illustrating a representative control methodaccording to the present disclosure, and FIG. 10 is a flowchartillustrating in detail a part of the control method shown in FIG. 9.FIGS. 11A, 11B, and 12 are conceptual views illustrating the methodillustrated in FIGS. 9 and 10.

The description given with reference to FIGS. 7A to 8 will be appliedequally/similarly to the following description.

The first mobile robot 100 a may include one antenna 710 a provided onone point of the first mobile robot and configured to transmit andreceive signals.

The second mobile robot 100 b may include a first antenna 710 b and asecond antenna 720 b which are provided on the front area of the mainbody 100 b and configured to transmit and receive signals to and fromthe antenna of the first mobile robot.

The control unit 1800 of the second mobile robot 100 b may determine therelative position of the first mobile robot using a signal receivedthrough the first antenna 710 b and the second antenna 720 b.

First, the control unit 1800 of the second mobile robot 100 b may outputa first signal (Radio message 1) to the first mobile robot 100 a throughat least one of the first antenna 710 b and the second antenna 720 bprovided in the second mobile robot 100 b (S910).

The control unit 1800 of the second mobile robot 100 b may control theUWB anchor 700 b to output the first signal through at least one of thefirst antenna 710 b and the second antenna 720 b.

To this end, the control unit of the first mobile robot 100 a mayreceive the first signal through the one antenna 710 a provided on onepoint of the first mobile robot 100 a.

The first signal may be, for example, a UWB signal. However, the presentdisclosure is not limited to this, and the first signal may include allthe signals that can pass through the first mobile robot 100 a or thesecond mobile robot 100 b.

The control unit of the first mobile robot 100 a may output a secondsignal to the second mobile robot 100 b, in response to the firstsignal.

The control unit of the first mobile robot 100 a may control the UWB tag700 a to output the second signal through the antenna 710 a of the firstmobile robot when the first signal is received.

Likewise, the second signal may be a UWB signal. However, the presentdisclosure is not limited to this, and the second signal may include allthe signals that can pass through the first mobile robot 100 a or thesecond mobile robot 100 b.

The second signal may include information related to a delay timet_reply which may be calculated based on a time at which the firstmobile robot 100 a has received the first signal and a time at which thefirst mobile robot 100 a has output (transmitted) the second signal.

The control unit 1800 of the second mobile robot 100 b may receive thesecond signal output from the antenna 710 a of the first mobile robotthrough each of the first antenna 710 b and the second antenna 720 bprovided on the front area of the second mobile robot (or the secondmobile robot main body) 100 b (S920).

When the second signal is received by the first antenna 710 b and thesecond antenna 720 b, respectively, the control unit 1800 of the secondmobile robot 100 b may determine a first distance between the antenna710 a of the first mobile robot and the first antenna 710 b of thesecond mobile robot and a second distance between the antenna 710 a ofthe first mobile robot and the second antenna 720 b of the second mobilerobot (S930).

In other words, the control unit 1800 of the second mobile robot 100 bmay determine the first distance between the antenna 710 a of the firstmobile robot and the first antenna 710 b of the second mobile robot andthe second distance between the antenna 710 a of the first mobile robotand the second antenna 720 b of the second mobile robot, on the basis ofthe signals (the first signal and the second signal) transmitted andreceived through the antenna 710 a of the first mobile robot and thefirst antenna 710 b and the second antenna 720 b of the second mobilerobot.

The method of determining (calculating) the first distance and thesecond distance can be understood in view of the description of FIG. 8.

The control unit 1800 of the second mobile robot 100 b may determine twointersections of two circles having the determined distances (the firstdistance and the second distance) as radii, respectively (S940).

Specifically, the control unit 1800 of the second mobile robot 100 b maydetermine two intersections of a first circle that the first antenna 710b is a center and the first distance is a radius and a second circlethat the second antenna 720 b is a center and the second distance is aradius.

The control unit 1800 of the second mobile robot 100 b may thendetermine a relative position of the first mobile robot 100 a (or aposition (relative position) of the antenna 710 a of the first mobilerobot), based on intensity of the signal (second signal) receivedthrough each of the first antenna 710 b and the second antenna 720 b(S950).

If the antenna of the first mobile robot 100 a and the first antenna 710b and the second antenna 710 b of the second mobile robot 100 b are alllocated on one straight line, the two circles may generate only oneintersection. In this case, the position (coordinates) corresponding tothe one intersection may be the relative position of the first mobilerobot (or the position of the antenna 710 a of the first mobile robot).

On the other hand, in more cases, the first antenna 710 b and the secondantenna 720 b of the second mobile robot 100 b may be disposed on thefront of the second mobile robot 100 b to be symmetric with respect tothe front of the second mobile robot 100 b, and the first mobile robot100 a may be located ahead of the second mobile robot 100 b. Thus, thecase where the antenna 710 a of the first mobile robot and the firstantenna 710 b of the second mobile robot of the second mobile robot areall placed on the straight line may occur less. Accordingly, the twocircles may generally have two intersections.

On the other hand, since the second mobile robot 100 b may be providedwith only the two antennas 710 b and 720 b, it may be problematic todetermine which of the two intersections is the relative position of thefirst mobile robot.

The present disclosure may determine one of the two intersections as therelative position of the first mobile robot based on the intensity ofthe signal received through the first antenna 710 b and the secondantenna 720 b.

In other words, the control unit 1800 of the second mobile robot 100 bmay determine whether the first mobile robot 100 a is located at thefront or rear of the second mobile robot with respect to the front ofthe second mobile robot 100 b, on the basis of the intensity of thesignal received through the first and second antennas 710 b and 720 b.

As illustrated in FIGS. 7A, 7B, and 8, the signals (the first signal andthe second signal) transmitted and received between the antenna 710 a ofthe first mobile robot and the first antenna 710 b and the secondantenna 720 b of the second mobile robot may pass through at least oneof the first mobile robot (or first mobile robot main body) 100 a andthe second mobile robot (or second mobile robot main body) 100 b.

However, when the signal passes through the second mobile robot 100 b,the intensity of the signal may be reduced.

When the signal does not pass through the second mobile robot 100 b, theintensity of the signal may not be reduced.

In addition, the intensity of the signal passing through the secondmobile robot 100 b may be weaker than the intensity of the signalwithout passing through the second mobile robot 100 b.

Conversely, the intensity of the signal without passing through thesecond mobile robot 100 b may be stronger than the intensity of thesignal passing through the second mobile robot 100 b.

Hereinafter, description will be given in more detail of a method ofdetermining one of the two intersections as the relative position of thefirst mobile robot, based on the intensity of the signal (second signal)received by the first and second antennas 710 b and 720 b.

Description given with reference to FIGS. 7A to 9 may be applied to theembodiment of FIG. 10 in the same or similar manner.

The first mobile robot 100 a may include one antenna 710 a provided onone point of the first mobile robot and configured to transmit andreceive signals.

The second mobile robot 100 b may include a first antenna 710 b and asecond antenna 720 b which may be provided on the front area of the mainbody 100 b and configured to transmit and receive signals to and fromthe antenna of the first mobile robot.

The control unit 1800 of the second mobile robot 100 b may determine therelative position of the first mobile robot using the signal receivedthrough the first antenna 710 b and the second antenna 720 b.

Referring to FIG. 10, when a signal is received through the firstantenna 710 b and the second antenna 720 b, respectively, the controlunit 1800 of the second mobile robot 100 b may determine (measure)intensity of the received signal. The intensity of the signal may beexpressed in the form of a value (or number, level).

The control unit 1800 of the second mobile robot 100 b may determinewhether the intensity of the signal (second signal) received by thefirst and second antennas 710 b and 720 b is greater than a referencevalue (S1010).

To this end, when the intensity of the received signal is greater thanthe reference value (or reference intensity), the control unit 1800 ofthe second mobile robot 100 b may determine an intersection, which maybe located at the front of the second mobile robot, of the twointersections, as the relative position of the first mobile robot(S1020).

For example, when the intensity of the signal (second signal) receivedby the first and second antennas 710 b and 720 b is greater than(greater than or equal to) the reference value (or reference intensity),the control unit of the second mobile robot 100 b may determine that thefirst mobile robot 100 a is located at the front of the second mobilerobot 100 b.

If the intensity of the received signal is smaller than the referencevalue (or the reference intensity), the control unit 1800 of the secondmobile robot 100 b may determine an intersection, which may be locatedat the rear of the second mobile robot, of the two intersections, as therelative position of the first mobile robot (S1030).

When the intensity of the signal (second signal) received by the firstand second antennas 710 b and 720 b is smaller than (smaller than orequal to) the reference value (or the reference intensity), the controlunit of the second mobile robot 100 b may determine that the firstmobile robot 100 a is located at the rear of the second mobile robot 100b. This is because the intensity of the signal output from the antenna710 a of the first mobile robot may be attenuated (reduced) as thesignal is received through the first and second antennas 710 b and 720b, located at the front of the second mobile robot 100 b, via the firstmobile robot (or first mobile robot main body) 100 a.

The reference value (reference intensity) may be determined (set) as avalue between the intensity of the signal when the signal has not passedthrough the second mobile robot 100 b and the intensity of the signalwhen the signal has passed through a predetermined section of the secondmobile robot 100 b.

The reference value may be determined by an experimental value at thetime of designing a product or determined/changed by user settingbecause of differences in output signal intensity of a signal outputbetween the first mobile robot and the second mobile robot, a degreethat signal intensity may be attenuated (deformed) according to amaterial of the second mobile robot (or main body), a length by which asignal passes through the second mobile robot, and the like.

The foregoing description will be made clearer with reference to FIGS.11A and 11B.

Description given with reference to FIGS. 7A to 10 may be applied to theembodiment illustrated in FIGS. 11A and 11B in the same or similarmanner.

The first mobile robot 100 a may include one antenna 710 a provided onone point of the first mobile robot and configured to transmit andreceive signals.

The second mobile robot 100 b may include a first antenna 710 b and asecond antenna 720 b which are provided on the front area of the mainbody 100 b and configured to transmit and receive signals to and fromthe antenna of the first mobile robot.

The control unit 1800 of the second mobile robot 100 b may determine therelative position of the first mobile robot using a signal receivedthrough the first antenna 710 b and the second antenna 720 b.

As illustrated in FIG. 11A, the control unit 1800 of the second mobilerobot 100 b may determine two intersections P1 and P2 between a firstcircle c1 that a first distance d1 between the antenna 710 a of thefirst mobile robot and the first antenna 710 b of the second mobilerobot 100 b may be a radius and the first antenna 710 b may be a centerand a second circle c2 that a second distance d2 between the antenna 710a of the first mobile robot and the second antenna 720 b of the secondmobile robot may be a radius and the second antenna 720 b may be acenter.

When intensity of the signal received through the first antenna 710 band the second antenna 720 b is equal to or greater than the referencevalue, the control unit 1800 of the second mobile robot 100 b maydetermine the intersection P1 located at the front F of the secondmobile robot, of the two intersections P1 and P2, as the relativeposition of the first mobile robot 100 a.

When the intensity of the signal received through the first antenna 710b and the second antenna 720 b is equal to or greater than the referencevalue, as illustrated in FIG. 11A, it may be a case where the firstmobile robot 100 a is located at the front of the second mobile robot100 b, the first and second antennas 710 b and 720 b are arranged on thefront area of the second mobile robot (or second mobile robot main body)100 b, and the signal received through the first antenna 720 b and thesecond antenna 720 b does not pass through the main body of the secondmobile robot 100 b.

On the other hand, as illustrated in FIG. 11B, the control unit 1800 ofthe second mobile robot 100 b may determine two intersections P3 and P4between a first circle c3 that a first distance d3 between the antenna710 a of the first mobile robot and the first antenna 710 b of thesecond mobile robot 100 b may be a radius and the first antenna 710 bmay be a center and a second circle c4 that a second distance d4 betweenthe antenna 710 a of the first mobile robot and the second antenna 720 bof the second mobile robot may be a radius and the second antenna 720 bmay be a center.

When the intensity of the signal received through the first antenna 710b and the second antenna 720 b is smaller than the reference value, thecontrol unit 1800 of the second mobile robot 100 b may determine theintersection P4 located at the rear R of the second mobile robot, of thetwo intersections P3 and P4, as the relative position of the firstmobile robot 100 a.

When the intensity of the signal received through the first antenna 710b and the second antenna 720 b is smaller than the reference value, asillustrated in FIG. 11B, it may be a case where the first mobile robot100 a is located at the rear of the second mobile robot 100 b, the firstand second antennas 710 b and 720 b are arranged on the front area ofthe second mobile robot (or second mobile robot main body) 100 b, andthe signal received through the first antenna 710 b and the secondantenna 720 b passes through the main body of the second mobile robot100 b by a predetermined length 1010.

When the signal passes through the second mobile robot 100 b by thepredetermined length 1010, the intensity of the signal may be reducedand may have a value smaller than the reference value.

The control unit of the second mobile robot 100 b may determine whetherthe intensity of the signal received through the first antenna 710 b andthe second antenna 720 b is equal to or greater than the reference valueor smaller than the reference value, and determine one of the twointersections as the relative position of the first mobile robot 100 abased on the determination.

When the relative position of the first mobile robot 100 a isdetermined, the control unit of the second mobile robot 100 b maycontrol the traveling unit 1300 to move the main body of the secondmobile robot 100 b toward the relative position of the first mobilerobot 100 a. That is, the control unit of the second mobile robot 100 bmay determine the relative position of the first mobile robot 100 a, andcontrol the second mobile robot main body to travel while following thefirst mobile robot 100 a based on the determined relative position.

The control unit of the second mobile robot 100 b may transmitinformation related to the determined relative position of the firstmobile robot 100 a to the first mobile robot 100 a through thecommunication unit. The control unit of the first mobile robot 100 a maydetermine the relative position of the second mobile robot 100 b basedon the information on the relative position of the second mobile robot100 b received from the second mobile robot 100 b.

The control unit of the first mobile robot 100 a may transmit a controlsignal to the second mobile robot 100 b to control various operations(for example, movement, rotation, following travel, stopping, travelingpath change, etc.) of the second mobile robot 100 b based on therelative position of the second mobile robot 100 b.

On the other hand, the control unit 1800 of the second mobile robot 100b may determine the position of the antenna 710 a provided on the firstmobile robot as the relative position of the first mobile robot.

In other words, the relative position of the first mobile robotdetermined by the second mobile robot 100 b may indicate a position ofone point where the antenna 710 a of the first mobile robot is disposed.

For example, when the antenna 710 a of the first mobile robot isprovided at the center c of the first mobile robot, the relativeposition of the first mobile robot determined by the control unit 1800of the second mobile robot 100 b may indicate the relative position ofthe center c of the first mobile robot with respect to the second mobilerobot (in detail, a middle point between the first and second antennas710 b and 720 b).

As another example, when the antenna 710 a of the first mobile robot isprovided at the rear side r1 of the first mobile robot, the relativeposition of the first mobile robot 100 b determined by the control unit1800 of the second mobile robot 100 b may indicate a relative positionof the rear side r1 of the first mobile robot with respect to the secondmobile robot (in detail, a middle point between the first and secondantennas 710 b and 720 b).

The relative position of the first mobile robot described in thisspecification may refer to a relative position of a point where the oneantenna 710 a of the first mobile robot is located.

On the other hand, when the antenna 710 a of the first mobile robot isprovided at the center of the first mobile robot, the signals (the firstsignal and the second signal) transmitted and received through theantenna 710 a of the first mobile robot may pass through the main bodyof the first mobile robot.

Since the antenna 710 a of the first mobile robot is disposed at thecenter of the first mobile robot and the first mobile robot 100 a isformed in a cylindrical shape, signals may pass through the first mobilerobot (or the first mobile robot main body) by the same/similarlength(s) based on omnidirectional positions of the antenna 710 a of thefirst mobile robot.

Accordingly, the intensity of the signal reduced due to passing throughthe first mobile robot (or first mobile robot main body) 100 a may notbe considered in the first and second antennas 710 b and 720 b of thesecond mobile robot.

On the other hand, when the antenna 710 a of the first mobile robot isprovided on the rear area (or rear side) r1 of the first mobile robot100 a, the intensity of the signal received in the first and secondantennas 710 b and 720 b of the second mobile robot may differ dependingon directions that the first mobile robot 100 a and the second mobilerobot 100 b face and an arrangement relationship of them.

FIG. 12 is a conceptual view illustrating a case where the second mobilerobot determines an arrangement relationship with the first mobile robotbased on intensity of a signal when the antenna of the first mobilerobot is disposed on the rear side of the first mobile robot.

Description given with reference to FIGS. 7A to 11 may be applied to theembodiment of FIG. 12 in the same or similar manner.

The control unit of the second mobile robot 100 b may determine thearrangement state of the first mobile robot 100 b and the second mobilerobot 100 b, based on the intensity of the signal received through thefirst antenna 710 b and the second antenna 720 b provided in the secondmobile robot 100 b.

Specifically, when the antenna 710 a of the first mobile robot isprovided on the rear side r1 of the first mobile robot 100 a and thefirst and second antennas 710 b and 720 b of the second mobile robot areprovided on the front areas f1 and f2 of the second mobile robot 100 a,the control unit 1800 of the second mobile robot 100 b may determine thearrangement state of the first and second mobile robots 100 a and 100 b(positions at which the first and second mobile robots 100 a and 100 bare located and directions that they face, or the arrangementrelationship of the first and second mobile robots 100 a and 100 b),based on the intensity of the signal received through the first andsecond antennas 710 b and 720 b.

For example, as illustrated in (a) of FIG. 12, when the first mobilerobot 100 a is located at the front of the second mobile robot 100 b andthe first mobile robot 100 a and the second mobile robot 100 b face thesame direction (i.e., the front side (or front area) F1 of the firstmobile robot 100 a and the front side (or front area) F2 of the secondmobile robot 100 b face the same direction), the first and secondantennas 710 b and 720 b may receive a signal output from the antenna710 a of the first mobile robot without passing through the first mobilerobot 100 a and the second mobile robot 100 b. Accordingly, intensity ofthe signal may have a first value (first intensity) which is the largestvalue.

The control unit 1800 of the second mobile robot 100 b may determinethat the first mobile robot 100 a is located at the front of the secondmobile robot 100 b and the first mobile robot 100 a and the secondmobile robot 100 b face the same direction, on the basis of the factthat the intensity of the signal received through the first and secondantennas 710 b and 720 b is the first value.

As another example, as illustrated in (b) of FIG. 12, when the firstmobile robot 100 a is located at the front of the second mobile robot100 b and the first mobile robot 100 a and the second mobile robot 100 bface each other (i.e., the front side (or front area) F1 of the firstmobile robot 100 a and the front side (or front area) F2 of the secondmobile robot 100 b face opposite directions from each other), the firstand second antennas 710 b and 720 b may receive the signal output fromthe antenna 710 a of the first mobile robot through the first mobilerobot 100 a by a predetermined length 1200 a. The signal may not passthrough the second mobile robot 100 b. Accordingly, the intensity of thesignal may have a second value (second intensity) which may be smallerthan the first value.

The control unit 1800 of the second mobile robot 100 b may determinethat the first mobile robot 100 a is located at the front of the secondmobile robot 100 b and the first mobile robot 100 a and the secondmobile robot 100 b face each other, on the basis of the fact that theintensity of the signal received through the first and second antennas710 b and 720 b is the second value.

As another example, as illustrated in (c) of FIG. 12, when the firstmobile robot 100 a is located at the rear of the second mobile robot 100b and the first mobile robot 100 a and the second mobile robot 100 bface opposite directions from each other (i.e., the front side (or frontarea) F1 of the first mobile robot 100 a and the front side (or frontarea) F2 of the second mobile robot 100 b face opposite directions fromeach other), the first and second antennas 710 b and 720 b may receivethe signal output from the antenna 710 a of the first mobile robotthrough the second mobile robot 100 b by a predetermined length 1200 b.The signal may pass through the first mobile robot 100 a. Accordingly,the intensity of the signal may have a third value (third intensity)which may be smaller than the first value.

The control unit 1800 of the second mobile robot 100 b may determinethat the first mobile robot 100 a is located at the rear of the secondmobile robot 100 b and the first mobile robot 100 a and the secondmobile robot 100 b face different directions from each other, on thebasis of the fact that the intensity of the signal received through thefirst and second antennas 710 b and 720 b is the third value.

The second value and the third value may be determined by experimentalvalues. The second value and the third value may also vary depending onthe sizes of the first and second mobile robots 100 a and 100 b, thematerials of the first and second mobile robots, and the like.

This is because the signal intensity differs depending on thecharacteristics of the first and second mobile robot main bodies, whichmay reduce the signal intensity because the signal may pass through onlyone main body of the first and second mobile robots.

For example, when the first mobile robot 100 a is larger than the secondmobile robot 100 b, the intensity (second value) of the signal which haspassed through the main body of the first mobile robot 100 a may beweaker than the intensity (third value) of the signal which has passedthrough the main body of the second mobile robot 100 b.

As another example, as illustrated in (d) of FIG. 12, when the firstmobile robot 100 a is located at the rear of the second mobile robot 100b and the first mobile robot 100 a and the second mobile robot 100 bface the same direction (i.e., the front side (or front area) F1 of thefirst mobile robot 100 a and the front side (or front area) F2 of thesecond mobile robot 100 b face the same direction), the first and secondantennas 710 b and 720 b may receive the signal output from the antenna710 a of the first mobile robot through the first mobile robot 100 a bya predetermined length 1200 d and through the second mobile robot 100 bby a predetermined length 1200 c. Accordingly, the intensity of thesignal may have a fourth value (fourth intensity) which is smaller thanthe first value, the second value and the third value.

The control unit 1800 of the second mobile robot 100 b may determinethat the first mobile robot 100 a is located at the rear of the secondmobile robot 100 b and the first mobile robot 100 a and the secondmobile robot 100 b face the same direction, on the basis of the factthat the intensity of the signal received through the first and secondantennas 710 b and 720 b is the fourth value.

The description that the first mobile robot 100 a and the second mobilerobot 100 b face a direction(s) may mean that the front side of thefirst mobile robot 100 a and the front side of the second mobile robot100 b face the direction(s).

When the first and second mobile robots 100 a and 100 b are arranged inthe state shown in (a) of FIG. 12, ideal following travel can beperformed.

On the other hand, when the first and second mobile robots 100 a and 100b are arranged in the states shown in (b) to (d) of FIG. 12, the controlunit 1800 of the second mobile robot 100 b may control at least one ofthe second mobile robot 100 b and the first mobile robot 100 a to be inthe state shown in (a) of FIG. 12.

For example, as shown in (b) of FIG. 12, when the first mobile robot 100a is located at the front of the second mobile robot 100 b and the firstmobile robot 100 a and the second mobile robot 100 b face each other,the control unit 1800 of the second mobile robot 100 b may transmit acontrol signal to the first mobile robot 100 a through the communicationunit so that the first mobile robot 100 a rotates in an oppositedirection (180-degree direction).

As another example, as illustrated in (c) of FIG. 12, the first mobilerobot 100 a is located at the rear of the second mobile robot 100 b andthe first mobile robot 100 a and the second mobile robot 100 b faceopposite directions, the control unit 1800 of the second mobile robot100 b may control the traveling unit 1300 such that the second mobilerobot 100 b is rotated in an opposite direction (180-degree direction).

As another example, as illustrated in (d) of FIG. 12, when the firstmobile robot 100 a is located at the rear of the second mobile robot 100b and the first mobile robot 100 a and the second mobile robot 100 bface the same direction, the control unit 1800 of the second mobilerobot 100 b may stop the movement of the second mobile robot 100 b andtransmit a control signal for controlling the first mobile robot 100 ato pass ahead the second mobile robot 100 b to the first mobile robot100 a through the communication unit 1100.

In addition, the control unit 1800 of the second mobile robot 100 b maycontrol the first mobile robot 100 a and the second mobile robot 10 b sothat the first mobile robot 100 a is located at the front of the secondmobile robot 100 b and the first mobile robot 100 a and the secondmobile robot 100 b face the same direction, as illustrated in (a) ofFIG. 12, which may allow the second mobile robot to smoothly follow thefirst mobile robot.

Even in the cases shown in (a) to (d) of FIG. 12, the control unit 1800of the second mobile robot 100 b may determine (recognize) the relativeposition of the first mobile robot 100 a in real time or atpredetermined intervals, by equally/similarly applying the descriptiongiven with reference to FIGS. 7A to 11B.

In addition, the control unit 1800 of the second mobile robot 100 b maytransmit (or share) information related to the determined relativeposition of the first mobile robot 100 a to (or with) the first mobilerobot 100 a through the communication unit.

Meanwhile, the second mobile robot 100 b of the present disclosure mayinclude two UWB anchors and two antennas, and determine the relativeposition of the first mobile robot 100 a using only the two UWB anchors(or two antennas).

The control unit of the second mobile robot 100 b may determinedirection information (angle information) where the first mobile robotis located with respect to the forward direction of the second mobilerobot, on the basis of a phase difference of signals received throughthe first antenna and the second antenna.

The first antenna and the second antenna may be connected to one UWBanchor or may be connected to different UWB anchors, respectively.

The second mobile robot 100 b may include a first UWB anchor connectedto the first antenna and a second UWB anchor connected to the secondantenna.

The control unit of the second mobile robot 100 b may determinedirection information where the first mobile robot is located withrespect to the forward direction of the second mobile robot on the basisof a phase difference between a signal received by the first UWB anchorthrough the first antenna and a signal received by the second UWB anchorthrough the second antenna.

The control unit of the second mobile robot 100 b may calculate distanceinformation up to the first mobile robot based on signals transmittedand received through the one antenna provided in the first mobile robotand at least one of the first antenna and the second antenna provided inthe second mobile robot.

The control unit of the second mobile robot 100 b may determine therelative position of the first mobile robot based on the calculateddistance information and the direction information.

For example, the control unit of the second mobile robot 100 b maydetermine direction information (angle information) where the firstmobile robot 100 a is located with respect to the forward direction ofthe second mobile robot 100 b, using only two UWB anchors (or twoantennas) other than three UWB anchors (or three antennas) in theaforementioned AoA manner.

To this end, the control unit of the second mobile robot 100 b mayreceive a signal output from the UWB tag of the first mobile robot 100 athrough the first UWB anchor and the second UWB anchor (or the firstantenna and the second antenna), respectively.

If a signal received through the first UWB anchor (first antenna) is afirst signal and a signal received through the second UWB anchor (secondantenna) is a second signal, the control unit of the second mobile robot100 b may determine a phase difference between the first signal and asecond signal.

In addition, the control unit of the second mobile robot 100 b may knowinformation on a distance between the first UWB anchor and the secondUWB anchor (or a distance between the first antenna and the secondantenna) in advance. The distance may be a value preset at the time ofmanufacture.

The control unit of the second mobile robot may calculate angleinformation where the first mobile robot is located with respect to theforward direction of the second mobile robot based on the phasedifference of the signals received in the first UWB anchor and thesecond UWB anchor (or the first and second antennas), and determinedirection information where the first mobile robot is located withrespect to the forward direction of the second mobile robot based on thecalculated angle information.

On the other hand, the control unit of the second mobile robot 100 b maycalculate distance information up to the first mobile robot 100 a basedon a time for which the signals are transmitted and received between thefirst module (UWB tag) of the first mobile robot 100 a and the secondmodule (UWB anchors) of the second mobile robot 100 b. That is, thecontrol unit of the second mobile robot 100 b may determine the distanceinformation between the first mobile robot 100 a and the second mobilerobot 100 b in the ToF manner.

The control unit of the second mobile robot 100 b may determine therelative position of the first mobile robot based on the calculateddistance information and the direction information.

The control unit of the second mobile robot 100 b may determine thedistance information through the ToF scheme and determine the directioninformation (or the angle information) through the AoA scheme.

The ToF scheme may need only one UWB tag and only one UWB anchorregardless of the number while the AoA scheme may need one UWB tag andat least two UWB anchors (or at least two antennas). Therefore, thefirst mobile robot 100 a of the present disclosure may be provided withone UWB tag and the second mobile robot 100 b may be provided with atleast two UWB anchors (at least two antennas).

The description of the AoA method of recognizing the relative positionof the first mobile robot 100 a (in detail, the angle information(direction information) related to the first mobile robot 100 a) usingthe two UWB anchors (or two antennas) may be equally/similarly appliedeven to a case of providing two antennas in one UWB anchor of the secondmobile robot 100 b.

When one UWB anchor has two antennas, the control unit of the secondmobile robot 100 b may receive a signal transmitted from the UWB tag ofthe first mobile robot 100 a via each of the two antennas, and determinedirection information (angle information) where the first mobile robot100 a is located with respect to the forward direction of the secondmobile robot 100 b, based on a phase difference of the received signaland a distance between the two antennas.

Meanwhile, when the second mobile robot 100 b is provided with two UWBanchors, each of the two anchors may be connected to two antennas.

For example, two antennas may be connected to a first UWB anchor, andtwo antennas may be connected to a second UWB anchor.

The first UWB anchor and the second UWB anchor may be symmetricallydisposed with respect to a blocking member formed to block the UWBsignal. For example, the blocking member may be a case (or a camera)formed of a metal material, and the case (or camera) may be provided ata central portion of the front area on the main body of the secondmobile robot 100 b.

The first UWB anchor and the two antennas connected to the first UWBanchor may be provided at a left side with respect to the blockingmember and the second UWB anchor and the two antennas connected to thesecond UWB anchor may be provided at a right side with respect to theblocking member.

The control unit of the second mobile robot 100 b may determine a UWBanchor which has received the UWB signal, of the first UWB anchor andthe second UWB anchor.

For example, when the UWB signal is received through the first UWBanchor, the control unit of the second mobile robot 100 b may determinethat the first mobile robot 100 a is located at the right side withrespect to the forward direction of the second mobile robot 100 b.

As another example, when the UWB signal is received through the secondUWB anchor, the control unit of the second mobile robot 100 b maydetermine that the first mobile robot 100 a is located at the right sidewith respect to the forward direction of the second mobile robot 100 b.

Thereafter, the control unit of the second mobile robot 100 b mayreceive the UWB signals respectively through the two antennas connectedto the UWB anchor (for example, the first UWB anchor) in which the UWBsignal has been sensed, and determine direction information (angleinformation) where the first mobile robot 100 a is located with respectto the forward direction of the second mobile robot 100 b, on the basisof a phase difference between the received UWB signals.

According to the present disclosure, the second mobile robot 100 b maybe provided with the two UWB anchors and each of the two anchors may beconnected to the two antennas, so that the direction information (angleinformation) of the first mobile robot can be calculated with respect tothe second mobile robot 100 b in the AoA manner even when the secondmobile robot 100 b is provided with the blocking member, which mayresult in widening a range capable of receiving the UWB signals.

Accordingly, the present disclosure may have an effect of significantlyincreasing a recognition rate of the relative position of the firstmobile robot.

The foregoing description may be applied to the method of controllingthe mobile robot (second mobile robot) 100 b in the same/similar manner.

For example, the method of controlling a mobile robot, in which a secondmobile robot determines a relative position of a first mobile robot, mayinclude determining a distance between an antenna of the first mobilerobot and a first antenna of the second mobile robot and a distancebetween the antenna of the first mobile robot and a second antenna ofthe second mobile robot when a signal is received through the firstantenna and the second antenna, determining two intersections of twocircles that the decided distances are radii, respectively, anddetermining one of the two intersections as the relative position of thefirst mobile robot based on intensity of the signal received through thefirst antenna and the second antenna.

The present disclosure provides a plurality of autonomous mobile robotsthat a second mobile robot can accurately determine a relative positionof a first mobile robot.

The present disclosure provides a plurality of new autonomous mobilerobots, capable of reducing costs while improving accuracy in a mannerthat a second mobile robot determines a relative position of a firstmobile robot using one UWB tag, one UWB anchor and the least antennas.

The present disclosure provides a plurality of new autonomous mobilerobots, capable of accurately determining a relative position of a firstmobile robot using only two receiving antennas, by use of the fact thata signal can be received through a main body and intensity of the signalcan be attenuated.

The present disclosure may calculate two intersections through a UWBmodule using a UWB signal and the least antennas, so as to enablecalculation of two accurate intersections and determination as towhether a first mobile robot is located at the front or rear of thesecond mobile robot based on intensity of a signal.

The present disclosure provides a plurality of autonomous mobile robots,capable of allowing smooth following by recognizing relative positionsthereof irrespective of a communication state with a server becauserelative positions of a first mobile robot and a second mobile robot canbe determined by the first and second mobile robots.

The functions/operations/control methods performed by the first mobilerobot 100 a disclosed herein may be performed by the control unit of thefirst mobile robot 100 a or the control unit of the second mobile robot100 b, and the functions/operations/control methods performed by thesecond mobile robot 100 b may be performed by the control unit of thesecond mobile robot 100 b or the control unit of the first mobile robot100 a.

In addition, the present disclosure may allow the second mobile robot100 b to determine the relative position of the first mobile robot 100a.

Since the first mobile robot 100 a may be the leading cleaner and thesecond mobile robot 100 b may be the following cleaner following thefirst mobile robot 100 b, the second mobile robot 100 b can more easilyfollow the first mobile robot 100 a by recognizing the relative positionof the first mobile robot 100 a, which may result in reducing accuracyof follow-up and calculation time of the relative position.

Since the first mobile robot may need to perform many calculations suchas detecting an obstacle according to a preset algorithm, creating mapinformation, determining a cleaning progress direction, and so on, suchcalculation load of the first mobile robot can be reduced as the secondmobile robot recognizes the relative position of the first mobile robot.

In this specification, description has been given of the example inwhich the second mobile robot 100 b may recognize the relative positionof the first mobile robot 100 a, but the present disclosure is notlimited to this.

In general, when a plurality of autonomous mobile robots exist and theirfollow-up control is performed, the first mobile robot may determine therelative position of the second mobile robot so as to increase accuracyand rapidity because the specification (Spec) of components provided inthe first mobile robot as the leading robot may be better thanspecification of components provided in the second mobile robot.

Accordingly, the present disclosure may allow the first mobile robot 100a to determine the relative position of the second mobile robot 100 b.

To this end, the control unit of the second mobile robot 100 b maytransmit information (for example, information related to each of theantenna 710 a of the first mobile robot and the first and secondantennas 710 b and 720 b of the second mobile robot, output timeinformation of a first signal, received time information of a secondsignal, delay time information (t_reply), or the like), calculated bythe control unit of the second mobile robot 100 b, to the first mobilerobot 100 a through the communication unit.

In this case, the control unit of the first mobile robot 100 a maydetermine the relative position of the second mobile robot 100 b (or therelative position of the first mobile robot 100 a with respect to thesecond mobile robot 100 b) based on the information received from thesecond mobile robot 100 b through the communication unit.

In order to determine (decide) the relative position of the secondmobile robot 100 b, the first mobile robot 100 a may include thosecomponents provided in the second mobile robot 100 b and the secondmobile robot 100 b may include those components provided in the firstmobile robot.

For example, the first mobile robot 100 a may include first and secondantennas and a UWB anchor, and the second mobile robot 100 b may includeone antenna and a UWB tag.

In this case, the control unit of the first mobile robot 100 a mayperform the functions/operations/control methods performed by thecontrol unit of the second mobile robot 100 b described in thisspecification, and the control unit of the second mobile robot 100 b mayperform the functions/operations/control methods performed by thecontrol unit of the first mobile robot 100 a.

Accordingly, the control unit of the first mobile robot 100 a maydetermine the relative position of the second mobile robot 100 b throughthe functions/operations/control methods performed by the control unitof the second mobile robot 100 b.

When the first mobile robot 100 a determines the relative position ofthe second mobile robot 100 b, the first mobile robot 100 a may transmitthe determined relative position information of the second mobile robot100 b to the second mobile robot 100 b. Further, the second mobile robot100 b may determine the relative position of the first mobile robot 100a based on the received relative position information of the secondmobile robot.

Whether the first mobile robot 100 a determines the relative position ofthe second mobile robot 100 b or the second mobile robot 100 bdetermines the relative position of the first mobile robot 100 a may bedecided at the time of product production, and may be determined/changedby user setting.

The present disclosure described above can be implemented ascomputer-readable codes on a program-recorded medium. The computerreadable medium includes all kinds of recording devices in which datareadable by a computer system is stored. Examples of thecomputer-readable medium include a hard disk drive (HDD), a solid statedisk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, amagnetic tape, a floppy disk, an optical data storage device and thelike. In addition, the computer may also include the control unit 1800.The above detailed description should not be limitedly construed in allaspects and should be considered as illustrative. The scope of thepresent disclosure should be determined by rational interpretation ofthe appended claims, and all changes within the scope of equivalents ofthe present disclosure are included in the scope of the presentdisclosure.

What is claimed is:
 1. A plurality of autonomous mobile robots,comprising: a first mobile robot having an antenna configured totransmit and receive a signal; and a second mobile robot having a firstantenna and a second antenna disposed on a front area of a main bodythereof, the first antenna and the second antenna being configured totransmit and receive signals to and from the antenna of the first mobilerobot, and wherein the second mobile robot comprises a control unitconfigured to determine a relative position of the first mobile robotusing the signal received by the first antenna and the second antenna,wherein the control unit of the second mobile robot is configured to:determine a first distance between the antenna of the first mobile robotand the first antenna, based on the signal transmitted and receivedthrough the antenna of the first mobile robot and the first antenna ofthe second mobile robot, determine a second distance between the antennaof the first mobile robot and the second antenna, based on the signaltransmitted and received through the antenna of the first mobile robotand the second antenna of the second mobile robot, and determine twointersections between a first circle and a second circle, wherein aradius of the first circle corresponds to the first distance, and acenter of the first circle corresponds to the first antenna, and whereina radius of the second circle corresponds to the second distance, and acenter of the second circle corresponds to the second antenna.
 2. Therobots of claim 1, wherein the first antenna and the second antenna aredisposed to be symmetric to each other in right and left directions withrespect to the front area of the main body.
 3. The robots of claim 1,wherein the first antenna and the second antenna are configured toreceive signals transmitted in directions except for a directiontraveling from the front area of the main body through the main body. 4.The robots of claim 1, wherein an intensity of the signal received inthe first antenna or the second antenna is reduced when the signal isreceived through the main body.
 5. The robots of claim 1, wherein anintensity of the signal received in the first antenna and the secondantenna without passing through the main body after being output fromthe antenna of the first mobile robot is stronger than an intensity ofthe signal received in the first antenna and the second antenna throughthe main body after being output from the antenna of the first mobilerobot.
 6. The robots of claim 1, wherein the control unit of the secondmobile robot is configured to: output a first signal to the first mobilerobot through at least one of the first antenna or the second antenna;receive a second signal output from the antenna of the first mobilerobot in each of the first antenna and the second antenna, and determinea first distance between the antenna of the first mobile robot and thefirst antenna and a second distance between the antenna of the firstmobile robot and the second antenna when the second signal is receivedin each of the first antenna and the second antenna.
 7. The robots ofclaim 1, wherein the control unit of the second mobile robot isconfigured to determine the relative position of the first mobile robotbased on an intensity of the signal received through the first antennaand the second antenna.
 8. The robots of claim 7, wherein the controlunit of the second mobile robot is configured to: determine twointersections between a first circle and a second circle, wherein aradius of the first circle corresponds to a first distance between theantenna of the first mobile robot and the first antenna, and a center ofthe first circle corresponds to the first antenna, and wherein a radiusof the second circle corresponds to a second distance between theantenna of the first mobile robot and the second antenna, and a centerof the second circle corresponds to the second antenna, and determine anintersection located at a front of the second mobile robot of the twointersections as the relative position of the first mobile robot whenthe intensity of the signal received through the first antenna and thesecond antenna is equal to or greater than a reference value.
 9. Therobots of claim 8, wherein the control unit of the second mobile robotis configured to determine an intersection located at a rear of thesecond mobile robot of the two intersections as the relative position ofthe first mobile robot when the intensity of the signal received throughthe first antenna and the second antenna is smaller than the referencevalue.
 10. The robots of claim 1, wherein the control unit of the secondmobile robot is configured to determine a position of the antenna of thefirst mobile robot as the relative position of the first mobile robot.11. The robots of claim 1, wherein the first mobile robot comprises anUltra-Wideband (UWB) tag to transmit and receive a UWB signal, andwherein the antenna of the first mobile robot is electrically connectedto the UWB tag.
 12. The robots of claim 1, wherein the second mobilerobot comprises an Ultra-Wideband (UWB) anchor to transmit and receive aUWB signal, and wherein the first antenna and the second antenna of thesecond mobile robot are electrically connected to the UWB anchor. 13.The robots of claim 1, wherein the control unit of the second mobilerobot is configured to determine an arrangement state of the firstmobile robot and the second mobile robot based on an intensity of thesignal received through the first antenna and the second antenna. 14.The robots of claim 1, wherein the control unit of the second mobilerobot is configured to determine a direction in which the first mobilerobot is located with respect to a front of the second mobile robot,based on a phase difference of the signal received through the firstantenna and the second antenna.
 15. The robots of claim 1, wherein thesecond mobile robot comprises: a first Ultra-Wideband (UWB) anchorconnected to the first antenna; and a second UWB anchor connected to thesecond antenna, wherein the control unit of the second mobile robot isconfigured to determine a direction in which the first mobile robot islocated with respect to a front of the second mobile robot, based on aphase difference between a signal received by the first UWB anchorthrough the first antenna and a signal received by the second UWB anchorthrough the second antenna.
 16. The robots of claim 15, wherein thecontrol unit of the second mobile robot is configured to: calculate adistance to the first mobile robot, based on signals transmitted andreceived through at least one of the antenna of the first mobile robot,the first antenna of the second mobile robot, or the second antenna ofthe second mobile robot, and determine the relative position of thefirst mobile robot based on the calculated distance and the direction.17. A method for controlling a mobile robot, the method comprising:determining, by a control unit of a mobile robot, a first distancebetween an antenna of the first mobile robot and a first antenna of thesecond mobile robot and a second distance between the antenna of thefirst mobile robot and a second antenna of the second mobile robot,respectively, when a signal is received through the first antenna andthe second antenna of the second mobile robot; determining, by thecontrol unit, two intersections between a first circle and a secondcircle, the first circle having the first distance as a radius and thesecond circle having the second distance as a radius; and determining,by the control unit, one of the two intersections as a relative positionof the first mobile robot based on an intensity of the signal receivedin the first antenna and the second antenna.